My Xperia 10 Single-SIM with the latest SFOS version randomly restarts. I can not see a pattern (time, application or anything else) to point me to a possible cause.
It is very annoying especially if you do not notice it and people try to contact you and your phone sits there with a log-in screen. It does this approximately 3 times in two days or thereabouts.
Jolla should alert that, let wait for next release
I have that, too. 
I thought, that it happens mostly with Android apps, but once it happened without AD turned on, so this is solely a SFOS problem.