It feels like macmini is sleeping secretly

The timemachine backup was not completed on the first day, prompting Time Machine did not complete the backup because some files were unavailable. The backup will continue after the Mac is unlocked. I got up this morning and found that WeChat has also been launched, but the programs I opened last night are still there. After checking the settings, sleep is not turned on. There has been no new mac version update in the past two days, and my automatic installation of updates is turned off. But after a few hours, it seems that he has restarted. Has anyone encountered it? https://i.imgur.com/acNeb9x.png