Ah, you made a point, I didn’t remember that regular Ubuntu has selinux enabled. I see other reports said that this is only happens on 5.0 kernels. I have mainline kernel because my mouse has problems which fixed in 5.0.8. I’ll try stock kernel tomorrow.
alvin@alvin-BM1AF:~$ snap debug sandbox-features
confinement-options: classic devmode
dbus: mediated-bus-access
kmod: mediated-modprobe
mount: freezer-cgroup-v1 layouts mount-namespace per-snap-persistency per-snap-profiles per-snap-updates per-snap-user-profiles stale-base-invalidation
seccomp: bpf-argument-filtering kernel:allow kernel:errno kernel:kill_process kernel:kill_thread kernel:log kernel:trace kernel:trap kernel:user_notif
udev: device-cgroup-v1 tagging
alvin@alvin-BM1AF:~$ snap version
snap 2.38+19.04
snapd 2.38+19.04
series 16
ubuntu 19.04
kernel 5.0.9-050009-generic
alvin@alvin-BM1AF:~$ snap list |grep -e core -e snapd
core 16-2.38 6673 stable canonical* core
core18 20190409 941 stable canonical* base
alvin@alvin-BM1AF:~$ mount |grep selinux
selinuxfs on /sys/fs/selinux type selinuxfs (rw,relatime)