I can't launch games on Steam for some reason, at least Windows games using Proton. I even reinstalled Steam several times, but nothing has changed. My distro is Pop OS. Here's what happens when I try launching Vanquish for example:

chdir "/home/quentin/.steam/debian-installation/steamapps/common/Vanquish"
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/ubuntu12_32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
Game Recording - would start recording game 460810, but recording for this game is disabled
Adding process 63931 for gameID 460810
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/ubuntu12_32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/ubuntu12_64/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS64): ignored.
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/ubuntu12_32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
ERROR: ld.so: object '/home/quentin/.steam/debian-installation/ubuntu12_32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
Adding process 63932 for gameID 460810
Adding process 63933 for gameID 460810
Adding process 63934 for gameID 460810
setlocale "fi_FI.UTF-8": No such file or directory
pv-locale-gen: Missing locale fi_FI.UTF-8 (found in $LC_ADDRESS)
pv-locale-gen: Generating locale fi_FI.UTF-8...
pv-locale-gen: Generated locale fi_FI.UTF-8 successfully
pv-locale-gen: Generating locale en_US.UTF-8...
pv-locale-gen: Generated locale en_US.UTF-8 successfully
pv-adverb[64004]: W: Container startup will be faster if missing locales are created at OS level
Adding process 64042 for gameID 460810
Adding process 64045 for gameID 460810
Adding process 64046 for gameID 460810
fsync: up and running.
Adding process 64047 for gameID 460810
Adding process 64050 for gameID 460810
Adding process 64052 for gameID 460810
Adding process 64056 for gameID 460810
Adding process 64068 for gameID 460810
Adding process 64074 for gameID 460810
Adding process 64081 for gameID 460810
Adding process 64113 for gameID 460810
Adding process 64122 for gameID 460810
Adding process 64125 for gameID 460810
Adding process 64132 for gameID 460810
Fossilize INFO: Overriding serialization path: "/home/quentin/.steam/debian-installation/steamapps/shadercache/460810/fozpipelinesv6/steamapprun_pipeline_cache".
pid 64048 != 64047, skipping destruction (fork without exec?)
Game Recording - game stopped [gameid=460810]
Removing process 64132 for gameID 460810

This has something to do with Steam's overlay, even though I have disabled it. Help is welcome.