The FOB spawn is overrun mechanic introduced in V12 is too effective. At it's core, I think this is a good mechanic as it prevents the meat grinder HAB camping and also allows FOBs to be taken down a bit more reliably. It also makes sense, once you have taken over an enemy FOB they shouldn't be able to spawn in there. However, the mechanic is extremely OP, for multiple reasons. For one, vehicles are able to disable HAB spawning. having any 2 manned vehicle within 30m of an enemy HAB effectively disables it. Unless you've got AT close by, it's often very difficult to prevent this from happening. It needs to be limited to only one person in the vehicle counting towards this effect, like it is for capturing flags. Another reason this mechanic is broken is in pretty much any decent FOB location, it is extremely easy to just have 2 people hiding 30m away from the HAB, which pretty much just means you can take over the FOB. even if you have less manpower, the enemy can't respawn and will soon be overrun. This makes super fobing and actually holding the point nearly impossible, as you are doomed the second 2 people get within the 30m radius.
Two examples of this are Mestia's quarry and Al Basrah's VCP. On both points, there is really only one building/compound to put your HAB structure in. And on both points, if the enemy has two players hiding anywhere on the outside wall of the building, the HAB is no longer able to be spawned on. This mechanic is really unhealthy to the meta for this reason. I like that it promotes building backup FOBs and more strategic HAB placement, but it is nearly impossible to have good HAB placement in V12 as it will always go down eventually. The solution to this problem is fairly simple, I already mentioned the first part which would be to have all players in vehicles only count as one player towards the disable. The other mechanic change would be to up it to 3 people to disable, as well as reduce the radius to at least 15m, although I feel 10m or 5m would be better. The overrun mechanic was a solid introduction to Squad, but the execution was slightly flawed.