Good list @Maximuuus. I think it combines "BG-ness" and "D&D 5e-ness," which you kind of mention.
BG-ness would be more "evoking the feeling/playstyle of BG1&2" -day/night -add dyes -better UI -worldmap -party size -party formations
5e-ness would be "is the game using the 5e rules and/or balanced based on 5e-like rules" -reactions? (idk how reaction/instant spells work in 2e) -backstab/high ground (kind of. High ground advantage/disadvantage mechanics? 5e-ness. High ground at all? Both 5e and BG-ness. But Larian is obviously not going to remove the existence of high ground) -HP bloat/AC reduction -action/bonus action + new actions
Both -cantrips shouldn't create surfaces -enemy special attack/items -less useless items and more d&d items -scroll usage -dipping -dice roll ability scores(?)
At least, this is how I'd quickly sort them.
Backstab and High ground are mainly homebrew rules (as there are actually implemented). They are awesome, they shouldn't remove them.
But they should probably rework them a lot, except if kangaroo, backstab and king of the hill are intended to be common "tactics".. not to say automatic tactics that do not require too much thinking.
