OpenGL app segfaults on qt-xcb(x11) and qt-wayland qpa on Qt6.4+

I upgraded my distro (MiniMyth2) from well working Qt6.3.2 to Qt 6.5.0 and I started to have segfaults when using in x11 or wayland qpa. Drawing to eglfs qpa works ok.

Qt 6.5.0 with drawing to X11 gives me segfault like this: https://gist.github.com/warpme/95abdde87d468ce8cf4bb2416159e6d4

The same binaries (qt6, mythtv) are working ok with drawing to eglfs.
(https://gist.github.com/warpme/cdc7e9a23bca4cb10c0433d880cc288d).

As issue:

1. starts to happen only when Qt6 is newer than 6.3
2. Verification of relevant qt6 dependencies looks ok (libs vers. verified with documentation; no any warnings from Qt configure)
3. all Qt versions older than Qt6.4 are working ok.

I'm not sure: is this Qt6 bug or Qt6.4+ change i need to address in my application (MythTV).

I tested following Qt versions with results like this:
(each time only qt was rebuild from sources)

• 5.15.9 - ok
• 6.2.3 - ok
• 6.3.2 - ok (last in v6.3 line)
• 6.4.0 - nok (first in v6.4 line)
• 6.4.3 - nok (last in v6.4 line)
• 6.5.0 - nok

 Are there any fundamental change in Qt6.4+ in OpenGL subsystem braking OpenGL apps compatibility?