JOSM freezes from time to time without clear indication why

[dieterdreist]

I get freezes in Josm several times a day, console output is this:

local revision is 18559, latest available revision is 18559 - using local revision 18559
starting josm...
josm started with PID 2504
2022-09-20 09:43:48.759 INFO: Log level is at INFO (INFO, 800)
Warning: the font "Times" is not available, so "Lucida Bright" has been substituted, but may have unexpected appearance or behavor. Re-enable the "Times" font to remove this warning.
Warning: the font "Times" is not available, so "Lucida Bright" has been substituted, but may have unexpected appearance or behavor. Re-enable the "Times" font to remove this warning.
2022-09-20 09:43:50.630 INFO: Detected no usable IPv6 network, preferring IPv4 over IPv6 after next restart.
2022-09-20 09:43:50.667 INFO: Restart [/Library/Java/JavaVirtualMachines/adoptopenjdk-8.jdk/Contents/Home/jre/bin/java, -Xmx2048M, -Djosm.home=/Users/martin/.josm-cai, -Dsun.java2d.opengl=true, -jar, /Users/martin/bin/josm-archive/josm-18559.jar]
josm terminated

it says "josm terminated", and "restart" but what I see in the GUI is Josm with a "waiting spinner" and neither restarting, nor being reactive to any command (I have to kill it and restart manually).

Also I always get {{{
preferring IPv4 over IPv6 after next restart
}}} (i.e. also after restart).