Sneak attack gets progressively more devastating and, importantly, the resource it spends refreshes each turn. Not round, turn.
That is true in 5e. In BG3 you must activate sneak attack with a special button, and that means that you do not get sneak attack die on attacks of opportunity (at least I don't think that you do, has anybody tested this?)
This is something that Larian should fix. I don't see why the special buttons are needed. Rogue should automatically get sneak attack on any attack that satisfies the conditions that allow it.
