This is very good. Can I uninstall snapd or do i needs that for some reason?
The link says: " [qubes-users] sanity-squashfs available and removed notifications
Jin-oh Kang Wed, 16 Oct 2019 09:14:18 -0700
A quick search reveals that it might be from snapd (snapcraft). Every time a Qube tries to attach a file to a loop device – perhaps to mount its filesystem – it’s still recognized as a block device (just like a USB flash drive as you mentioned) and a udev script notifies the Dom0 about the event.
If it continues to bother you, just create a ‘.qubes-exclude-block-devices’ (without the quotes) file in the /tmp directory. It should silence all loop attaches from it, not just sanity-squashfs-290*. Should it not work, you can kill the Qubes block devices tray icon process which is afaik responsible for all the notifications iirc. --"