Following the rules established by the setting is a big one. If I'm constantly thinking "Wait what? That's not how that works?" I'm getting pulled out of the story. The rules can be fantastical but they should be consistent. If the established rules are broken, it should framed as or acknowledged as such. Breaking established rules can be a plot point, that's fine, but just fudging it to move the plot forward is a problem.

Characters acting in line with their characterization. Characters obviously change, and that includes making choices that are otherwise out of character- but those should be treated as such. I'm talking about the more mundane, unacknowledged flip flopping that obviously just pushes a plot forward.

Characters in entirely fictional settings should have some thought put into their values. A character from a post-apocalyptic setting that's reformed into a medieval type culture should not talk like or have the values of an American in 2026. Or, an American teenager in 2026 who talks like an out of touch Boomer (because they were written by one) is similarly distracting.

In anything other than pure comedy having restraint with quips and humor. Not every character should be a snarker, and snark shouldn't be used to undercut moments meant to be taken seriously. The tone depends on the characters, and too much tonal whiplash is immersion breaking.

In positives, if it is an entirely fictional setting, some thought to how it works goes a long way. I don't need to know the math on logistics, but if a small isolated fictional settlement has an obvious food and water source that passes the eyeball check for plausibility then it removes a potential distraction for someone wondering how it works. This applies to money, governments, currency, all sorts of things. There doesn't need to be a total breakdown how it all works but creating at least the appearance of functioning systems makes a setting more real.

A lot of this is subjective, and almost all stories can be criticized for some of this, but there's a breaking point which a majority of audiences is probably going to find themselves not getting into the story.