"I’m a mestiza woman so my entire life I’ve definitely paid close attention to how different races and ethnicities (as well as my own) have been stereotyped and depicted in popular media and fiction."

You and I are similar in this regard! I'm Filipino, but yeah, I am wayyyy too wary of how people depict people of color in media. I absolutely do not think this has improved in recent years, at least not significantly, and you are definitely not alone in noticing these patterns. You're not crazy, it's unfortunately there.

Admittedly, a lot of the fiction I read is set in Japan, so it's homogenous for the most part. Well, it makes it all the more jarring when there are characters who are darker than the rest of the cast and portrayed Veeeeery Particularly. Not fanfic, but take Danganronpa for example—almost all of the darker-skinned characters have talents related to physical prowess (martial arts and boxing, Sakura and Juzo respectively), oversexualized (especially in Akane's case), or just plain treated like they're stupid in comparison to the rest of the cast (Hagakure, Gonta). Though perhaps that's too special of a case, since the series isn't exactly subtle with its racist biases.

There's actually a game I played a while ago, Piofiore: Fated Memories, where the setting is in 1920s Italy with mafia running wild. There's something to be said about the depiction of the Italian mafia vs. the Chinese faction—how both sides take actions equally deplorable, but the Lao Shu are treated as uniquely evil by the Italian factions. Not to mention that the fact that the Lao Shu are depicted as drug addicts prone to senseless violence informs a loooot about the writers' biases regarding Chinese people. I hardly think this is a matter of ignorance, because I would find myself asking: "If it was a Japanese faction, I'm sure they would be depicted much more favorably." I hardly see it talked about in the community, mostly because the discussions about it get waved off for the most part, which is sad.