I discovered a bug that appears in any 6.13 kernel within quemu but not in any 6.12 kernel.
I use quemu-9.2.2 to run windows10 in it and there I use a program called sprint-layout-6.0.
This program saves and loads his files via samba, so I have them on my linux-ext4 disk and not in the disk-file quemu uses.
It worked for years now and it still works with all 6.12.x kernels up to now.
But it does not work with any 6.13.x kernel up to date.
The bug shows up when I try to load a file from within this program, then the emulated windows10 pops up a window with "exeption 8000004".
I do not know what this is trying to tell me, but under any 6.12.x and older kernels this did not happen.
So I assume a bug in 6.13.x kernel is the cause.
I also reported this to qemu but got now answer up to now.
Any help is welcome, thanks.