I am on 12.1 and it is happening with all files.
It is an issue with my user account and PS as I have
a service user where photoshop worked ok.
I was desperate so I have now used Time Machine to
go back to last week, unfortunately I forgot to save the
PSErrorLog.txt file first.
I think the issue arose due to a client sending a file with
the wrong extension. This is not unusual, PS doesn't recognise
file type and then I change the extension until I get the correct one
for the file, bingo it opens.
On this occasion I tried all the usual possible extensions without
any luck but unfortunately I couldn't open any other files after