Filesystem errors in guest system using Gnome Boxes flatpak

Setup: Silverblue 31 with gnome boxes 3.34.1 flatpak
Since upgrading to the new silverblue release, gnome boxes causes filesystem errors on the guest system (ubuntu 18.04 LTS). After using the guest system for a while, filesystem errors occur, often noticed because the filesystem inside the guest system is suddenly read only.
Running fsck inside the guest system often helps at the beginning, but after some time, the guest system cannot be fixed anymore.
In such cases, it is also not possible to restore a previous snapshot.
This now happend for the fifth time within the last four weeks.
For now, I had to do a clean install of the guest system every time this errors occurred.
Is anyone else experiencing these kind of problems with silverblue and gnome boxes?