Now I was able to download the symbols.
gdb qt6ct
(gdb) run
Starting program: /usr/bin/qt6ct
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".
[New Thread 0xfffff240ef60 (LWP 26116)]
[New Thread 0xfffff1a0ef60 (LWP 26117)]
Downloading separate debug info for /usr/lib/qt6/plugins/platformthemes/libqt6ct.so...
[...]
Downloading separate debug info for /usr/lib/qt6/plugins/imageformats/libqsvg.so...
Thread 1 "qt6ct" received signal SIGSEGV, Segmentation fault.
0x0000fffff6675e18 in ?? ()
from /usr/lib/libQt6Core.so.6
(gdb)
Is that enough?
Other app that had debug in binary:
Thread 1 "<app>" received signal SIGSEGV, Segmentation fault.
0x0000fffff5075e18 in ?? () from /usr/lib/libQt6Core.so.6
(gdb)