Support and reviving.
Not enough people revive. Mostly because it takes too long. In its current form it is just not good. Also I would buff the score reward for reviving to encourage players reviving. Support is still popular but not because they want to resupply or revive they play support to heal themselves or play with LMGs. This is the real issue. Squad revive without squad members that you know (like friends) basically non existent. Nobody cares about reviving at all.
Defibrillator needs changing. Everybody who revives with defib just click use without charging it which brings you back to life with 50 hp. It should revive with 100 hp even without fully charged. It takes a gadget slot. It should not require charging up you could as well just drag revive then and pull the body to safety. 99% of times I get revived by defib I just die 0.1 sec on the ground. Can't do anything about it. Of course lot of times the support just revives without looking around or someone just camps my corpse and snipes it once I'm revived which is kind of innevitable but what could be a good change is this. After you get revived get a short adrenalin rush type of thing that makes you move faster so you can get up from the ground faster. Maybe even a slight DMG reduction. Not for long maybe for like 0.5 seconds or so. I think it would make sense. It is not really abuseable.
Just do something with it.