Destruction of a T-90A and T-72B by FPV drones.

https://lemmy.ca/post/4432844

Destruction of a T-90A and T-72B by FPV drones. - Lemmy.ca

What is the warhead on these things?

Answering my own question it appears to be a PTAB bomb: en.wikipedia.org/wiki/PTAB_(bomb)

I don’t understand how this video resulted in a kill though; I don’t think the turrent-top armor would be a “weak spot” that a PTAB could exploit. Maybe the issue was the open hatch?

PTAB (bomb) - Wikipedia

The open hatch almost definitely lead to the kill. You can overpressure loaded or stored shells with less than the .62kg explosive charge in the bomb. There’s a small chance though that it penetrated; T90a has at most 200mm of armor, of which 90mm is steel; PTAB have been known to penetrate 90mm of steel and the rest of the armor composite does not resist HEAT rounds.
Most of the time it is an RPG warhead