>Level scaling applied to the whole world whether it makes sense or not
Oblivion is probably the worst offender. Level scaling was applied to everything and was immersion breaking. If you happened across a legendary weapon early on, its stats were scaled to be similar to ones of a low-tier weapon. On the flipside, in late game you had common roadside bandits running around in daedric armor worth tens of thousands but still shaking down people for 50 coins. Equipment that was worth fortune and should have been rare became common. And many lower level creatures were replaced by high level ones, rendering scamps for example nearly extinct by the time you reached max level.
Ironically, Morrowind did it best. Most of the level scaling was applied in certain spots and it made more sense. The higher the quality of equipment, the more scarce it was in the world. Usually buried in a challenging dungeon or in possession of someone powerful. You could still encounter weaker daedra, undead, and animals even at max level.
>Game where you and the AI should be more or less 1:1 opponents but the AI gets to ignore the rules and mechanics to make it more challenging or fair because devs can't code a proper opponent
This probably bothered me the most in Civ V. AI gets to practically ignore happiness mechanic so it can spam cities to take over whole coastlines or resource nodes with no penalties. On higher difficulties AI gets tech and other bonuses so playing a game on these settings means always following the same script of always rushing science and wonders that help yo keep up and ignoring most other mechanics for the first couple hours of the game. This annoyed me so much that I haven't touched any game with Sid Meyer's name on it since Civ V.