Created attachment 180177 [details]
Debug log from gdb

SUMMARY
I use cachy os, a derivative of arch linux with an AMD 9070 XT gpu. After a system update kmail shows graphical glibber in the message preview window. All other windows and menus show proper text, only the message preview window below the message list is affected. From all the other kde programms i use (kate, dolphin, konsole only one wiget named "ChatAI" has the same problem. To investigate further I installed a fresh version of cachy. In this installation kmail doesn't even start on the first start, it show the window of the import wizard, but the main window crashes when showing the welcome message.
Then i tried to start kmail on the pc of my wife (same os, same state of software but nvidia graphic card). Kmail started without any problems. So I assume its a problem with kmail and/or its libraries and the mesa dirver I use. I tried mesa 25.0.3-2 and mesa-git 25.1.0-devel.203961.3d7bfcf9845-1. Same results.

In the attachment you'll find a gdb log of the crash starting kmail. I thought it might be easier to track a problem that happens right at the start of the program.

It might be important to know that kmail worked on this os before the system update. The mesa library was updated form version 25.0.2-2 (worked) to version 25.0.3-2.

STEPS TO REPRODUCE
1. Install an os with the above mentioned mesa version
2. Start Kmail
3. Crash?

OBSERVED RESULT
'kmail' terminated by signal SIGSEGV (Address boundary error)

EXPECTED RESULT
Normal start up

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: cachy os
KDE Plasma Version: 6.3.4
KDE Frameworks Version: 6.12.0
Qt Version: 6.9

ADDITIONAL INFORMATION