Uhm Stug has been buffed greatly, PzIV is only poor vs inf without the MG upgrade, T-34/76 is only good when RNG is on your side, some times it wipe a Pak in 2 shot, other times it fail to kill a pio squad. And Ostheer no longer goes T4, so what's the point of Soviet goes T4 also? SU-85 only exists to kill Panther and Tiger, for everything else T-34/76 is better.
The stug is doing a half assed job as a generalist which overlaps with the p4 role. This is a bit of a problem as you have no decent mobile anti-heavy AT units until you reach the panther . however reaching the panther in 1vs1 is not only expensive fuel wise but also mp wise.
p4 does have AI issues as relic in the past decided to t-34 should be more AI and the p4 more AT hence the higher scatter. but with the t-34 buff this no longer applies and the t-34 is the better tank in both AI and slightly in AT