From I updated my phone it's been randomly restarting like 3 different times per day and it's really frustrating to see I'm using my phone for work it just shuts off and close out my applications. Samsung you need to sort this out urgently. I've seen also that multiple people with Note20/ Ultra are having the same problem from they've upgraded to the June software update.
Mine too. Someone posted on another thread today that Samsung is aware and is working on a security patch update to fix the issue. Hopes to be released next week. That's what the poster said.