How does post penetration HEAT damage work in warthuder? From what I understand, there are more damage or fragments the more residual penetration is left.

For example, 90mm HEATFS with 300mm pen vs the 280mm or so of the T95. It penetrates, but does barely any damage. maybe will turn a crew member yellow at most
Meanwhile, if you fire the same 90mm HEATFS at something like a panther, it does enough damage to basically nuke the crew

Maybe that explains why the 40mm grenades and 30mm HEDP ammo on helicopters does barely any damage at all.