Thank you all very much for your answers!
It's a good advice, and I'd love to get it checked by someone. It's just a bit difficult to find the right person, as generally, existing readers don't really like to get spoiled, and it's a bit difficult to ask someone with no interest to my comic to read 20+ pages for context. But I may be able to exchange that against another service with a friend.
I don't think I'm in this kind of position, but it may be, as you noted earlier, blindness, and I may not realize that it's actually what's happening. I don't know.
I'll put a bit more context under spoiler at the end of the message.
This is the most difficult for me I think. I actually started publishing last year very early after even discovering the existence of webcomics, because I thought that if I was not starting publishing very early with clearly beginner skills, and waited to get better.. I would NEVER publish anything because I would always look for more and more perfection. I find it easy to be very, very imperfect than pretty good but not as good as I want.
That part I put in bold... Happens just... all the time!
Not the problem in this case (see spoiler at end of my message) but it does occur to me a lot. Sometimes I just drop the idea, sometimes I recycle it somewhere else, and sometimes it starts a new subplot, which is something I won't do anymore in the future because my story is going out of hands with subplots 
Ah yes, true, I'm never entirely happy, and know I will never be regardless of how much I may improve in the future. I only judge the quality of a page relatively to other recent pages, I suppose that's the safest, and the fairest.
Good to know!
I think I'll finish this section, get one or two people to check it, and if there is nothing shocking to them, I'll work toward the 'accepting below average pages' solution 
More info on problem for those who'd be interested:
Spoiler
So the scene I have problem with is a funeral scene. Very, very simple funeral, just a pyre and 2 (living) characters, the dead person and a semi-materialized manifestation of a goddess.
The scene is important for the plot, but not really more than any other scene (it's a very contemplative comic with many subplots, no scene is immensely more important than the previous one). However, I had my main characters preparing for the funeral at the end of chapter one, and jumping directly to events happening after the funeral would require changing things in the next 30 pages or so, to reintroduce in a different way all the info supposed to be given during the funeral, which I'm not ready to do.
Now, the whole funeral scene is about 10 pages long, but I only have a problem for the 2-3 last pages with the manifestation of the goddess. All the info is there, but it looks very underwhelming. To give an idea of the ambiance I'd like: before being a comic, I wrote that story for a musical project, and that scene was supposed to be an instrumental piece with sarangi as the main instrument, with this kind of ambiance : https://www.youtube.com/watch?v=2gi6aG6DDMY (starting at 0:19. Obviously NOT my composition, but similar ambiance).
It's VERY emotional and spiritual music to me, which worked great to evoke vividly a divinity presence, and I can't even start to obtain something similar in drawing, I know it's partially due to the fact my drawing skills are pretty low at this time, but I felt I did better in conveying specific ambiances in other pages, so I'm a bit disappointed I can't get something I like for this scene. (For eg. just before the appearance of the goddess I have a panel with a completely ablaze pyre that I know have many mistakes, but I love it and it sets just the right ambiance).
As I'm writing I'm wondering if the problem is that I set too high standards to myself for these few pages; then getting them read by someone else would be very essential as they could tell me if they see the quality dropping between the page I like very much and the next pages.. Maybe I'm creating problems that don't exist?