Same issue here, no HDR with my Q90T when i choose performance mode on Ps5 meaning 4k120Hz
It's a well known issue with all 2020 premium Samsung TV's.
Apparently it only happens with Ps5 as with new XBox there's no such problem.
LG Tv's on the other hand are able to output 4K 120HZ with HDR.
Lets hope its not a harware issue and an upcoming update will fix it.
How can I see if I have these problems? I bought the TV new for the PS5 and don´t know how to see an fps counter or something else. I have an Q82T and would like to know if these models have the problem too...