My very much armchair-general -level understanding is that they do work against simple detonation-on-impact -drones, as long as there’s only few. The tank armor can brush off the shrapnel from explosion (crew might need new boxers and/or pants) but once there’s a hole in that afro the second (or third or…) drone can use that hole and get to the meaty bits. Or a skilled FPV operator can find a existing gap and use that.

So that does more than nothing, but ideally tank should have infantry support to keep drones and individual enemies with a bazooka away from it.