You will need to install the new kernel to reduce the temperature of your Pi4. It looks like yours is still using the old kernel even after the update. If you are only using it as a player the best way is probably PiCorePlayer but it seems a waste to use a Pi4 purely as a player. I ended up going back to Raspbian Buster and installing LMS but I don’t use mine as a player. Works perfectly and sits at around 42 degrees in a FLIRC case.