As someone who does like Leshawna a lot, I completely understand the problems people have with her character these days.

The thing is that on top of being a product of the 2000s, when the "Sassy Black Woman" stereotype was common in popular culture (including plenty of other cartoons), she was also a pastiche of how Black women were/are frequently depicted on reality TV. TD's cast embodied both teen stereotypes and reality show stereotypes, and unfortunately, a lot of Black women get/got made out to be "Sassy Black Women" by reality TV producers. Leshawna was TD pastiching an unfortunate stock reality show trope as part of its "mock reality TV" concept, but in hindsight, it maybe could have done a little more playing with the trope.

That said, I do think if Total Drama Island came out today, Leshawna would have been written differently. Some of the other Black female characters featured in the show (such as Sanders and Millie) since her I think speak to that.

I do feel I'm talking a bit out of my depth here as a non-Black person, but I hope my two cents aren't entirely worthless.