"I must do a backup", I thought, as Ubuntu rebooted after an update
...
blk_update_request: I/O error, dev sdb...
blk_update_request: I/O error, dev sdb...
blk_update_request: I/O error, dev sdb...
blk_update_request: I/O error, dev sdb...

#linux #fffffffuuuuuuuuuuu

@scruss If finally implemented btrbk from my Ubuntu lunar laptop to my Synology and 4 days later the SSD started freezing.