MIUI 12.5 Enhanced Edition has been wreaking havoc for some POCO F3 handsets. The device's random reboot issue has been acknowledged though, and a fixed build will arrive later this week.
https://www.notebookcheck.net/Xiaomi-POCO-F3-random-reboot-issue-following-MIUI-12-5-Enhanced-Edition-upgrade-acknowledged.560928.0.html