Fully restarted after "START_PRINT"

Hi, I have a v-core 3.1 300mm with the standard kit configuration (no mods).

Recently, something weird happened.
I started a print; the probing and both heatings were fine.

But after heating to printing temp, RatOS fully restarted without any errors. The print log also shows nothing.
I can't figure out what exactly caused the restart.

Has anyone encountered similar issues?

Many thanks!