I see a history of this problem over the years in Galaxy phones. But it happened to me for the first time at a wedding this weekend on my S23 Ultra. Recorded father's dance with bride, and after 3 mins, the phone just stopped recording & went to locked screen. File was lost, nowhere to be found. I had installed the 6.1.1 update a few days before.
I'm not sure about the file being lost, but the phone generally goes to the lock screen like that and stopped recording because it has overheated from what I understand. It happened to me once before when I was using an s23 recording in 8k
I have seen this before, what the user didn't realize is the user memory is almost full and this cases this if the phone isn't over heating. You have to either clean up the memory and store the file on the cloud or on a computer or a thumb drive this will solve the issue. Also check the video settings and reduce the resolution the high the resolution is set for the larger the file size
