I think I called this out a long time ago, here I'm showing that many fuel tanks on vehicles have a barrier before the 7BZ3 round can hit a barrier before the fuel tank, which completely deadens the incendiary effect - no matter how thin that barrier is. This means that for many vehicles, 7BZ3 cannot start fires. Only vehicles with exposed fuel tanks can be set alight. This impacts gameplay for anyone who carries such ammo, as they may take it in order to do some anti materiel shenanigans only to be let down when they try to set fires. The only real use in that case for 7BZ3 is the same as the standard AP round that the americans have for their marksman rifle - to better penetrate barriers and armour. The video shows clearly that whilst exposed tanks can be set alight by 7BZ3, tracers from an sa-58 have a better time of it for many vehicles.
I have also noticed this barrier deadening effect is also partly experienced by 14.5x114mm API rounds. The APIT has the strongest incendiary effect.