Comment # 5 on bug 1099974 from Stefan Dirsch

The only possibly relevant difference might be

--- Xorg.8.log.formatted        2018-07-03 15:28:04.802211000 +0200
+++ Xorg.8.log.old.formatted    2018-07-03 15:28:12.999221000 +0200
[...]
+ (--) Depth 24 pixmap format is 32 bpp

Have you tried more simpler examples like

- glxinfo
- glxinfo

(Mesa-demo-x package)