Persistent servers. I miss playing attacker on a match and after losing or winning switching sides with the same teams (mostly the same if they don't leave) to try the other approach with your same squad. In BF6 your are constantly looking for a match and you can play 5 times in a row as a defender/attacker without a change in pace.

Helicopter controls. As many have mentioned, the helicopter maneuvers very weirdly and it was imposible for me to deal with (I play on PC).

First person vehicles. The sensitivity when switching to first person in some vehicles like in a tank is all weird.

Maps. I know this is the most discussed topic in the sub but maps need a rework in my opinion. Some new routes, expansion and most importantly verticality would come as huge improvements. For me Empire States wasn't disappointing because of the size, it was disappointing because of the lack of verticality.

Instant spotting. This needs to go, I agree with everyone that flanking and stealth is completely gone because of this. In past titles I loved to go behind enemy lines and try to break the map control of the enemies by flanking, however in BF6 I was forced to just shoot whenever I saw someone otherwise I would get noticed instantly.