No matter which game I try launching in Steam they all stop running soon after pressing "play". In the system report crash log I always find this error for every game: "The package providing /usr/bin/python3.9 could not be found."
When checking this folder manually I have "python3.10".

I have tried reinstalling this python version. Even though it looks like this worked judging from the terminal I still get this error.

Hello!

would be nice to give us more details, what OS is it, and exactly what did you try, what's happened.
http://www.catb.org/~esr/faqs/smart-...html#beprecise

My bad. I just installed Linux Mint 21.3 Virginia, installed Steam + proton experimental and 8.0, then some games to try: Ratchet & Clank Rift Apart, Days Gone, Palworld. All giving the same error described.

My bad. I installed Linux Mint 21.3 Virginia yesterday along with Steam and Proton experimental and 8.0 version. The went and downloaded a few games: Ratchet & Clank Rift Apart, Days Gone, Bloons TD6 and Palworld. They all give the error described above. I press "play", then it switches to "stop" as it is launching, then back to "play" as it gives up due to the python error every time.

When it comes to what I tried I mostly just went on forums like stackoverflow and copy pasted apt commands in the terminal like for reinstalling and getting dependencies and such. I'm not sure what I did in detail. However I know one was reinstalling and updating python. I seem to have a newer version of python than what the games expect me to have.

ok, probably try this: https://techviewleo.com/install-late...tu-linux-mint/

Your solution worked in getting python3.9 to show up inside the folder. Now the crash reports look different as well. The crash reports for python 3.9 now changed to this: https://termbin.com/ncmg

However I am still unable to play the games. The same issue with pressing play only for a game to try to launch and then stop like before still happens.

probably it is just a permission issue, it has no access right to those libraries.
I would suggest you to contact the official support.