I know I say this a lot, but I think feedback is best treated like UX (User Experience) research.
Think of it like this: Most people who use your product, ie. read your comic, are users. Users are very good at finding things that don't work well, whether you're testing a game, navigating a supermarket or reading a comic, because there are a lot of them and they go in just wanting to use the product. If they keep getting stuck on one boss because the attack pattern isn't obvious, if they can't find which aisle has the ketchup, if they keep getting two characters mixed up, they're not incorrect for saying so. Users are great at finding problems, so if they say "I couldn't get into it, it was a bit slow" or "IDK, I just don't like this comic's style" assume that they're not incorrect, and if there's a lot of feedback like that on a comic that seems to be struggling to build an audience, it's good to assume the readers have potentially identified a problem, or in UX terms, a "pain point" that's making them not have a good experience with the product.
BUT after collecting all this data of what the pain points are from users, you should then not necessarily listen to anything they say about how to fix those issues, and instead seek out somebody with a broader picture of the industry, more experience and more expertise to fix it.
Because if the issue is "I don't like the art style", a reader will often suggest, "So change it to an art style I like more" as the fix, when a better solution might be "host your comic somewhere else" or "market it to people who like this style more", or even "change the cover so it better reflects the style of the internal art, so you don't attract readers expecting something different."
Basically treat all feedback as valid, but be pragmatic about what advice you follow for fixing issues, because an awful lot of it will come from people who either haven't actually got a clue how to make a popular comic, or if they made a popular comic they don't really know how they did it (they just emulated the work of others and it happened to work out), or they don't actually care about helping you achieve your goal, they just want you and others to value what they value.
You also need to be honest about what you want to achieve and choose an appropriate critic too, or the critic can't help you. The number of times somebody comes to me like "Critique please! Do me! Do me!" and I advise them based on the assumption that they would like a comic with more readers (because mine has) or to get featured by Tapas or a Tapas contract (again, I tick both these boxes) or do professional work (yep! That's me!) and then after all that work, they turn around like "Oh, well, if it involves changing things about my work, I don't want a bigger audience or to be popular on Tapas or to do professional work, I think that stuff's for hacks, I just want to express my artistic vision through my comics." It's like.... Don't waste my freaking time, then! Just go and do that! Also putting the people who post in critique threads just to get exposure in a popular thread (or maybe under the delusion the critic will be awed into only saying nice things about how their comic is a hidden, underappreciated gem???) and then get angry because they got criticised on blast because RRRGHHHH! That is always infuriating and very disrespectful to the person who read through a bunch of your comic and formed opinions, gave advice, maybe even linked specific tutorials or did draw-overs. Never do that.
Look at reader feedback. Find the problems people are generally noticing, or common points of confusion about your story (or, if nobody's commenting at all, that might be a problem too, or a big drop off in readership at a certain point). Then try to find a critic who has had a greater degree of success at the thing you're trying to do. Do not expect good criticism from somebody who generally has a low opinion of the sort of thing you want to make. The critic doesn't have to draw or write just like you, but they can't hate the style or genre you want to work in, or their opinions be tinted by that. The best advice will always come from somebody who genuinely wants you to succeed and sees what you're making as valuable and worthwhile and really, truly does want to help you make the best version of what you want to make in order to achieve your goals.