updating my post with steam logs, I'm observing mentions of "/run/host/usr" paths next to pressure-vessel related erros:
steam-runtime-launcher-service[331499]: I: Running spawn command lsb_release
pressure-vessel-wrap[332000]: W: "run/host/usr/lib/ld-linux-x86-64.so.2" is unlikely to appear in "/run/host"
pressure-vessel-wrap[332000]: W: "run/host/usr/lib/ld-linux-x86-64.so.2" is unlikely to appear in "/run/host"
steam-runtime-launcher-service[331499]: I: Running spawn command lspci
steam-runtime-launcher-service[331499]: I: Running spawn command lsb_release
pressure-vessel-wrap[332000]: W: "run/host/usr/lib32/ld-linux.so.2" is unlikely to appear in "/run/host"
pressure-vessel-wrap[332000]: W: "run/host/usr/lib32/ld-linux.so.2" is unlikely to appear in "/run/host"
bwrap: execvp /usr/lib/pressure-vessel/from-host/libexec/steam-runtime-tools-0/pv-adverb: Too many levels of symbolic links
[331707:331707:0402/142238.243084:ERROR:atom_cache.cc(229)] Add _NET_WM_STATE_KEEP_ABOVE to kAtomsToCache
pressure-vessel-wrap[332143]: W: "run/host/usr/lib/ld-linux-x86-64.so.2" is unlikely to appear in "/run/host"
pressure-vessel-wrap[332143]: W: "run/host/usr/lib/ld-linux-x86-64.so.2" is unlikely to appear in "/run/host"
pressure-vessel-wrap[332143]: W: "run/host/usr/lib32/ld-linux.so.2" is unlikely to appear in "/run/host"
pressure-vessel-wrap[332143]: W: "run/host/usr/lib32/ld-linux.so.2" is unlikely to appear in "/run/host"
bwrap: execvp /usr/lib/pressure-vessel/from-host/libexec/steam-runtime-tools-0/pv-adverb: Too many levels of symbolic links
The mis-labelling is because the Steam client is now running inside a container, which has various parts of the real machine's filesystem mounted at paths inside the container. When it chooses a default name for a Steam library, it tries to use the mount point for the filesystem containing that directory, as an approximate Linux equivalent of Windows drive letters; but because different parts of the same filesystem are mounted in several places inside the container, it gets confused, and chooses the first one that appears in the mount table (or possibly the last one), which in your case happens to be the real machine's /usr mounted on the container's /run/host/usr.
Nothing extracted yet.
Your system information
/home/l1q/.local/share/Steam//home/l1q/.local/share/Steam/steamapps/common/Please describe your issue in as much detail as possible:
Normal beta version reports my root drive as "Local Drive (/)", SteamRT3 calls it "/run/host/usr" everywhere. The actual install paths, "browse local files" and similar actions work as usual.
Steps for reproducing this issue:
Screenshots
Expected:
Normal beta game install dialog
Normal beta game installed files
Normal beta Storage Settings
SteamRT3:
SteamRT3 game install dialog
SteamRT3 game installed files
SteamRT3 Storage Settings