Is it just me ?

i totally agree

manga usually has a much more interesting and prettier artstyle purely because of the limitation of colour making them use absence of colour and shading tricks to make it visually appealing, but sometimes the author goes overboard and it’s hard to read

compared to full-colour where it’s just simple and clean

it doesn’t help that manga has the troupes i hate the most lol

For me I never understand the space in which they're in, seeing them in anime is so weird bc the rooms make sense there but not in the manga

Uh... Honestly no, it's still good. I's more a matter of authors than a matter of media, I think.
For instance it's really a pain to follow the action in JuJutsu Kaisen, whereas it flows very naturally in Berserk (I'm trying to find very well-known mangas). And if we want the opposite case, Solo Levelling (at least how it was before the author's death, I dropped the series then) has action scenes that look very cool while being needlessly hard to follow, while Dam Of The Forest has a very efficient way of picturing the action.
I'm guessing you're comparing traditional manga with webtoons (one long vertical strip). Traditional mangas usually follow a cinematographic logic while webtoons have another style of narration entirely. It may just be that you find the webtoons' narration easier to follow.
Btw while writing this I actually had a lot of trouble finding a positive example among the webtoon-format stories I read. The only good ones that came to mind were the occidental ones like Lore Olympus, Stray Souls etc. (available for free on Webtoon you're welcome) but the narration's so different I wouldn't dare call them manga/hwa/hua.

And sometimes I feel panels are missing too

Yesss like they're in a situation/position in one panel and all of a sudden they're in a completely different one when is literally physically impossible

(づ￣ ³￣)づ ╮(￣▽￣)╭ I used to enjoy reading non colored manga and I tried reading certain ones I used to read now they don’t make sense to me

I know some people would be annoyed with this but I throughly believe that non colored manga should have direction through out the manga and notes if they feel something is missing in translation
I also have a belief that they are not posting the whole thing

Srry but this keep bugging me, manga is naturally non colored maybe you just prefer manhwas(?