Cartoons went from the majority of them having a unique enough art style to distinguish them from one another. If you take a silhouette of heads/faces from cartoon characters in the 90s and 2000s ( don’t have experience with prior decades besides the standard MGM cartoons, Jetsons/Flintstones, or things like Looney Tunes or Tom and Jerry ) you’d be able to tell the characters apart, even if you don’t even know who they are. Try doing that with most all 2010s and upwards new cartoon characters and you’ll get the exact same ugly, generic, and sanitized bean shaped head/face/smile imaginable.

There have definitely been some examples that might deviate a little from that mold, like Summer Camp Island, but those are far and few between anymore.

Also, for the most part, I would consider the overall quality as having been declining as well. I haven’t seen a lot of shows, so my experience should be taken with a huge lump of salt, but besides shows like Steven Universe, Summer Camp Island, etcetera, the storytelling hasn’t been as tight ( all of this in my opinion ), they’re banking on you not actually paying attention to the show itself so they can cheap out on every single step, art style is being sanitized and overly simplified to cut costs, and jokes are all devolving into “LOL RANDOM”, but that might have been a 2010s thing and I hope it’s dead.

It also doesn’t help that fans and fandom culture over time have become worse as well as you’ll usually find a vocal minority who will kick and scream while doxxing you because you ship the wrong 2 fictional characters together or don’t believe their exact highly specific headcannon, regardless of whether you are the creator or nor. Though, I’m debating of getting rid of this section because it might bleed too much into social media.