Not loading config file since 0.6.1 when Steam is "chrooted"

[Bumbadawg]

It worked perfectly in 0.5 and less, now it will not load my absolute set path to configfile.

Steam launch command LC_ALL=en_US.utf8 HOME=${XDG_DATA_HOME}/steam_clean /bin/steam 2>&1
Global vars :

export MANGOHUD=1
export MANGOHUD_CONFIGFILE="${XDG_CONFIG_HOME}/MangoHud/MangoHud.conf"

Steam log: (replaced absolute home path with $HOME)

INFO: process vulkandriverquery is blacklisted in MangoHud
skipping config: $HOME/.local/share/Steam/ubuntu12_64/MangoHud.conf [ not found ]
skipping config: $HOME/.config/MangoHud/vulkandriverquery.conf [ not found ]
parsing config: $HOME/.config/MangoHud/MangoHud.conf [ ok ]

Proton game log from the same Steam instance:
skipping config: $HOME/.config/MangoHud/MangoHud.conf [ not found ]

It seems Steam loads default config ( $XDG_CONFIG_HOME/MangoHud/MangoHud.conf) file, but not the subprocess game/app.
NB: the config file is perfectly loaded outside of Steam.

Even if the Steam proton subprocess exec somewhere through some chroot of its own, the path is set as absolute.

EDIT: it seems the subprocess exec screws up the actual $HOME with a user1000 one... Any workaround ?

_v2-entry-point[3589]: STEAM_COMPAT_APP_ID=1017900
_v2-entry-point[3589]: STEAM_COMPAT_SESSION_ID=9774773c9e954e6c
_v2-entry-point[3589]: XDG_RUNTIME_DIR=/run/user/1000
_v2-entry-point[3611]: STEAM_COMPAT_APP_ID=1017900
_v2-entry-point[3611]: STEAM_COMPAT_SESSION_ID=9774773c9e954e6c
_v2-entry-point[3611]: XDG_RUNTIME_DIR=/run/user/1000
esync: up and running.
_v2-entry-point[3990]: STEAM_COMPAT_APP_ID=1017900
_v2-entry-point[3990]: STEAM_COMPAT_SESSION_ID=9774773c9e954e6c
_v2-entry-point[3990]: XDG_RUNTIME_DIR=/run/user/1000
Installing breakpad exception handler for appid(steam)/version(1603992987)
_v2-entry-point[4009]: STEAM_COMPAT_APP_ID=1017900
_v2-entry-point[4009]: STEAM_COMPAT_SESSION_ID=9774773c9e954e6c
_v2-entry-point[4009]: XDG_RUNTIME_DIR=/run/user/1000

EDIT #2: fixed it, found out it was not related to 0.6 but to Proton 5.13 on a Steam runtime update #369 (comment)
closing this issue.

[Bumbadawg]

As for the vulkandriverquery Steam error, people report this is due to out of date driver. It runs Linux5.9 and Nvidia 450.80.02. Is this normal ?