Very boring bland protagonists, ones that are nearly imperfect. Ones that you can't really feel anything towards because of how vanilla they are.
Angry aloof protagonists that don't have any personality outside being annoyed or brusque and no motive for that behavior.
An asshole that gets no consequence for their actions, being an asshole also makes them complex because they're an asshole who cries and has some hamfisted backstory and you're suppose to relate to them. It ends up feeling like you're witnessing a relative you don't care much about go through turmoil or succeed at something and you're just like "okay... great, whatever."
Political protagonists. Oh my god those are the worst. The story ends up just being a very long PSA about some issue instead of a story and it's awful. Strawmen everywhere, no subtlety and depending where you stand on the issue you don't even care too much about it either because the protagonist is always right.