Player visibility
the problem with detecting sight isnt that it makes the game even playable beyond guessing where your enemy is in the cloud of smoke you create everytime your gun fires, it is the ridiculous muzzle flash that is the issue, lower that and not using it does not put you at such a disadvantage.
I see that there is a flash hider attachment now, but it is useless compared to the detecting sight as it basically is a flash hider that gets rid of every smoke particle (enemy, self, grenade) all the while being a competent sight attachment
Double-time
Since there is such an issue with 'peakers-advantage' in this game, nerfing double time would alleviate that issue. gameplay will be less slow and pre-aimming before turning corners, and instead be more encouraging of proactive engagement.
The whole reason why snipers were nerfed in the first place is because of this, they are not enjoyable to use unless you use it very specifically because the only way they are viable against actual good players is by pre-aiming which is not really fun, even the fastest snipers are relatively slow. Since ARs aim faster than Snipers you are almost always already caught by a flinch if you were using Sniper against AR with your opponent reacting at the same time, in which case you would have to hope the random flinch lands you a lucky body shot or headshot
Even without those considerations in mind the Double-time perk is stupid OP to begin with, nobody runs anything other than that
Flinching
Flinching should be adjusted so that it isnt as affected by damage amount, so that SMGs and snipers are more on par with ARs.
LMGs & recoil
LMGs are useless other than the two that are somewhat alright. Do away with the ridiculous random recoil on LMGs and some maybe some SMGs
These suggestions will probably never be added as they are not very concrete and is very drastic but I can't help but feel like they would change the game for the better, feel free to disagree.