Created attachment 867794 [details]
ltrace output

This is for gnome-mahjongg-3.40.0-1.1.x86_64
installed 2023-06-06; the symptom started then.  

It goes into an infinite loop about 10%-20% of the time.  No screen
action, no messages on stderr-stdout, no response to mouse clicks,
doesn't exiting when you click the X box in the window border
controls; just one core running flat out.  It does respond to SIGTERM
and SIGINT.  Sometimes it starts looping immediately when started;
sometimes you make a few (under 5) moves in the game and then it
loops, but it never (or rarely?) goes loopy in the moddle of game 
play. 

gnome-sudoku-44.0-1.2.x86_64 (and earlier) does not have the problem. 

I'm uploading ltrace output in case some clue is visible.  Command:

    ltrace -f -o /tmp/mjg.ltr -C -n 2 -S gnome-mahjongg 

Args: -f = trace forked processes; -o = output file; -C = demangle C++
symbols (none seen); -n 2 = indent in shared objects; -S = report 
system calls.

This time it went into a loop immediately on startup.  I let it run
about 5sec then killed with ^C (SIGINT). 384074 lines of output
recorded, 24Mb.  After 19500 lines (5%) it seems to have gotten into
a steady state.  I've truncated the file at this point to save space
on your server.  

4 processes are interleaved.  
It's repeating these library calls, per PID:  
    7799: g_utf8_strdown g_strcmp0 g_strdup g_ascii_strtod g_free 
	(and repeat)
    7812: begins and resumes futex 
    7813: begins and resumes futex 
    7814: begins and resumes restart_syscall (can't tell which syscall)