How can I debug an issue where a specific commit breaks transparency?

[zhengxianwei]

> > | * cb787d0c566 - (2 months ago) win32u: Use a pbuffer to implement GL

on memory DCs. - Rémi Bernon

This commit caused one of my images to go from transparent to
non-transparent.

How should I debug this?

I tried using RenderDoc to capture, but it errors out saying that on Linux
it supports the core profile and not the compatibility profile.

When I capture a trace with apitrace, it seems the program isn’t using a
standard OpenGL frame rendering flow.

May I ask what the default method is in Wine for debugging OpenGL or
investigating incorrect/garbled rendering?