4k Mode is actually 1728p on both PS5 and Series X with S at 1080p in it's sole mode.
Performance mode is 1080p 60fps on both consoles and are pretty much locked according to Mackenzie and is the suggested way to play.
There is no upscaling tech so the game can look a little blurrier on console vs other crossgen games.
The shadows look sharper on PS5, he suggests it's filtered differently vs XBOX.