Recently, fedora GNOME atomic (silverblue) freezes

It happened 3 times while inspecting a sql file in text editor and today a pdf in pdf viewer.

How can I catch the bug / error message?

The first times it happened it resolved by itself but I have to use the computer which is why I just restart when it happens. Everything is saved always, nothing is lost.

I’ve got 16 GB RAM and a i7 processor. It’s not the system. I use silverblue for more than a year.

After a restart does:
journalctl -b -1 -p 4 provide you any additional information.
You may also want to look at:
fpaste --sysinfo --printonly