if a teller took 99% of a T-70 or a stuarts HP a single faust or a 222 can easily knock it out... not exactly that difficult to knock out
besides a similar argument could be presented with the old democharge OHKing squads which was (rightfully but over) nerfed...
Another aproach could be to lower the damage significant (400-240/200) and giving it a bit more utility against vehicles by changing the damaged engine to a heavy engine damage. This would make it easier to do some follow up damage against light vehicles, stops even 320 hp vehicles from getting oneshottet and would be a lot more useful in the lategame against mediums or way overextending rare heavy vehicles.
If Tellermines get changed in this way they might lower the usage of riegelmines even more though.