I remember reading books by Stephen King where he would write an entire page about the garden of some character. I could never appreciate those details back then ...
Aaah, King is a master writer though! When I would do that it just got silly due to my inexperience haha. But I've gotten much, much better over the years. 
Oh and keeping secrets! I'm spoon feeding, but I dunno if that's the right thing to do? It's supposed to be mysterious, but I hope it's not annoying. 
Every one suspects themself of at least one of the cardinal virtues, and this is mine: I am one of the most self-indulgent people that I have ever known.
Without getting too self-analytical I know I struggle to write transition scenes. Like if the characters need to go from one place to another I find it hard to fill the gaps in between and make it feel interesting 
I suck at pacing.
I don't want to put to many panels in a page, but then I only put a few and it seems like I'm just dragging a scene out, and I'm just like. Oh no, will people find this boring? This is my first webcomic where I've like... committed to finishing it. And when I write the script, it seems fine, but when it comes to drawing it, it seems poorly paced even though my crew that I show this stuff to on a regular basis says its fine.
I'm also bad at small details. I have aphantasia, so when I read books I just...kinda skip over visual details. LotR was BORING AF to me because it's all this beautifully written prose about the location, but since I can't visualize, it kinda falls flat on me. So, when I draw, I'm working off of very basic written descriptions, because it doesn't matter to ME when I read, but I gotta remember that my readers don't have a broken brain like I do, and I need to be a little more detailed 
I have a really bad habit of repeating adjectives and descriptor words unnecessarily without changing them up. I usually catch this in revision. But I've been told I use words like "Incredulous" and "Vehemently" too much. This usually happens when I get to a scene I'm struggling to get out. Either because I'm not sure how to set it up, or where it's gonna go. I tend to "muscle through" those moments and repeat words way way way too often.
I also repeat actions a lot when I can't think of something for the characters to do in a scene. My characters chuckle too much or brush their hair aside a lot. I've actually learned to compensate for this by giving one of my characters a smoking habit so that I have something to fill a line with when I run out of ideas.
It's less a problem for readers a more just a problem for me as it makes editing that much harder.
Action scenes. I love action scenes but I can't write a decent one, for real. They end up too artificial, boring, or even out of character. Probably because my creative background is basically making digital RPGs, where all the action scenes were Final Fantasy-like battles, so I never had to worry about it before XD
I swear, next time I struggle with an action scene, I'm just gonna do the thing on RPG Maker and use screenshots of it as comic panels.
My writing is very stream of consciousness that jumps from past to present to dialogue to recollection. When done well its part of my unique style but sometimes it confuses the reader and makes my work inaccessible to those who aren't used to it.
This may sound funny, but I got my start writing with online fantasy roleplay. (World of Warcraft specifically) We would do detailed D&D style RP events weekly that involved paragraph long posts of combat scenes. My action scenes are always pretty in-depth, and I attribute most of that to my time with online RP. If you ever wanna get better at writing an action sequence, you might consider giving that a try. 
I'm so obsessed with subverting expectations and stereotypes that often I avoid necessary plot mechanics
Man, I wish I could play tabletop RPGs... but I get really, uhm, stiff? I can't act. I never role-played a full game because I'm way too shy for acting, and I take too long to write my dialogue, it's weird. Interesting suggestion, though. Does it still count if I role-play with myself only? XD
I don't see why not. I grew up a theater kid so I'm not as shy as others. But online roleplay where there's not direct contact between you and the other players is what really helped my writing. Even if you don't want to delve too far into it, you might consider researching RP world-building and Dungeon Master strategies. As a DM you're basically telling a story which the Players are acting out. There are guides out there that help you become a better DM, and I've found they really help writers as well. Or at the very least they've helped me.
Can't do numbers and don't trust my numbers because I very easily forget them and always have to go back to my spreadsheets and notes.
You have no idea how much this slows down my writing or just puts projects on halt.
I, as a narrator, am unsure all the time. I use 'perhaps', 'maybe', 'could be', etc all the time. Like, literally all the time. Not only that my characters don't know what's happening, I do not, too. Also, I like to info dump a lot. Sometimes even unnecessary info. Otherwise, I'll be too secretive to the point of not revealing anything. I can never find an middle point for it. And, well, I tell a lot; instead of balancing between telling and showing. I find it really difficult to show.
I have a really good feeling that.
In comics- I have a very limited amount of angles that I can place into my panels and that will most likely cause damage to the overall likability of the book.
In writing- A single chapter is 4000 words, a mini arc can last 4 chapters
In general- my stuff gets super dark at times, i really have no idea why but I have to have a super serious comic despite my mind restraints to do so.
I'm a notorious head hopper. On the positive side, I've never switched heads mid-paragraph, but you will know what all the characters are thinking. I had to resort to first person for my novel to keep myself from doing it - which I may end up keeping since I love writing bitter snark, and this lets me do even more.
The nice thing about comics is everyone can have a thought bubble! I just have to keep myself from abusing it... I also really wanna exposition dump in a prologue. Like, here's the world, lemme tell you all about it before we do anything else! So I'll sometimes write myself a prologue or something just to get it out of my system.
For me it was similar, but Harry Potter (set in the Marauder period) RP. 
Each post/reply was like a chapter long.
I really liked the collaborative story making though, and it eventually got me into writing original stories. 
My weakness is I can't make anything that's just simple. That sounds like a humble-brag, but it's not, it's a legit problem and frustration with my work, because complex stories with deep lore aren't intrinsically better, and some of my absolute favourite comics are actually very simple and straightforward in concept, but the content itself is really good, like say "Azumanga Daioh" which is just "some girls are at a generic Japanese high school and they say funny stuff".
As an example, I tried to write a vampire lesbian romance novel. Straightforward concept, it should be "ordinary woman meets sexy, dangerous seeming vampire with heart of gold, then they must spend time together to overcome a problem and while doing so, they fall in love."
But as soon as I started thinking about vampires, my brain was off down this rabbit hole of vampire lore, twists and turns the story could take, and I ended up with an overcomplicated story with too many characters that wanted to devote so much time to this complex vampire lore and the difficulties of overcoming the big bad that it wasn't really a romance story any more. 
I honestly do wish I could just make something that's simple, to the point and easy to sell by not getting distracted by intricacies and then having them eclipse everything else to the detriment of narrative and genre clarity, it'd make my work a lot more accessible (and profitable).