As it should. The Panther sacrifices the 60 range of other tank destroyers/ hunters for frontal armor. Further a Panther without frontal armor would be silly. This game is not about absolute realism but is influenced by it. A strength of the Panther should be decent frontal armor.
2.SU-85
Oh boy. Where do I start? This supposed 'tank destroyer' bonces shots at a panther.
The Su-85 could do with some price decrease though.
The same as above. It is not meant to frontally engage Panthers.
3.T34/85
Needs a serious damage and penetration buff. It should be able to reliably penetrate the frontal armor of panthers.
The T-34/85 outperforms the Panzer IV easily and has the health of a Panther. It is strong enough. The only flaw I see, is it being doctrinal.