What is one thing you would change on BF6?

For me it has to be Reworking Headshots to minimize the need for Hollow Points or synthetic tip, especially on pistols where you do not get enough points to, generally any weapon with base damage of 25 or lower hardly gets any benefit from more headshot damage, but higher damage weapons get more benefit. with sidearms this is why the M44 and M357 Trait are the best options despite the skill check. others such as GGH-22 and ES 5.7 just suck even with HP ammo (Still not a great point investment), With pistols might as well increase the base HSM for free since you lack the freedom to make meaningful tradeoffs anyways (due to 60 point cap, expensive attachments, lack of attachments, etc.)

Other than that, The most realistic change I'd want is either A clear all Orange Dot button or Remove or reduce 3D spotting when firing (AKA 3D spot on fire range) because using anything other than Flash hider or suppressors is too punishing for gameplay and distance spotted, instead DICE nerfed suppressors instead of solving the root of the problem. 

A far out change but one that can be impactful is to revert the Med Pen to heal The user instead of the effect which it has now that are worthless since you die faster than you can benefit from it. Just make it like the one in 2042, you didn't need any other effect or carry 4 or 5 in the beta, just make it so you spawn with 1 and must replenish it at a supply crate. That way assault actually has a decent class gadget and still rely on teammates to push OBJ.