Since the worst examples I can think of have already been mentioned, I'll just throw in that Boku No Hero Academia is making me pretty sad these days. It's like they decided to stretch out a few things that were shorter in the manga for a reason and it's gone on for so long that it doesn't feel like the same story at all anymore. I miss what the show used to be.
ETA: Ascendance of a Bookworm was really fun right up until she decides to dump everything in the trash and join the church.
I find this kinda fascinating because if you've thought this your entire life, you would have had to have read every intended plural "you" as singular and there would be nothing to inform you otherwise without very explicit context.
For the record, every 2nd person pronoun in the preceding paragraph can be singular or plural and still be grammatically correct while remaining socially correct for my speaking to an audience of unknown size. "You all" and "you guys" are slang phrases that don't appear in formal writing.