Cannot launch snap applications with cgroup v2

[mborzecki]

This appears to be the source of the problem:

@haslersn

2021/11/25 21:58:24.258005 tracking.go:45: DEBUG: creating transient scope snap.firefox.firefox
2021/11/25 21:58:24.258047 tracking.go:188: DEBUG: session bus is not available: cannot find session bus
2021/11/25 21:58:24.258057 cmd_run.go:1187: DEBUG: snapd cannot track the started application

Snap run attempts to create a separate scope (a cgroup actually) for the application by talking to org.freedesktop.systemd1.Manager over session bus. In your case, the session bus is unavailable, so a separate cgroup cannot be created thus it is not possible to set up device access rules or identify processes belonging to a snap.

Hwoever, it does appear that the process was in /user.slice/user-1000.slice/session-1.scope cgroup, what suggest that the session was at least partially set up by systemd. Can you check whether DBUS_SESSION_BUS_ADDRESS is set in your environment? (and in the terminal you execute the command). Does /run/user/1000/bus exist and is it a socket?