You think that's bad, check out some of the municipal flags in Japan, especially the ones designed in the early 2000s. The ones based on old clan symbols are fine, but those other ones look like some corpo bro from the 90s commissioned designs by saying "I want it to have more radical swoosh vibes!"
I don't have any art background so I can't really describe why the (non-clan based ones) feel so overly artificial. I think the color choice has a lot to do with it though-- way too many lime greens and oranges for me. Plus some of them are based on letters from the latin alphabet, which almost seems like a reverse weeb thing, ie "western letters are so cool guys!" Not that most of the kana ones are much better-- it's hard to make lettering on a flag look good.
Maybe the vexillology community would be able to describe it better.
edit: I mistook the comment I replied to as a reply to my comment below, but I'll leave this up as an explanation into why I find the Japanese flags strange
I can see where you’re coming from (in regards to Japanese prefecture flags) but I still think a lot of them look really good. At least the nicest thing is that they’re all consistent, but still a bit distinct from each other. And a symbol on a blanket is waaaay better than the american seal on a blanket in my opinion :)