The HW looks quite old… I remember of some issues reported on gitlab about old GPU drivers not properly advertising their opengl capabilities, that’s probably the case here.
You can force the GSK_RENDERER value in the app with GLib.setenv, at early startup, but that may negatively impact other users… Better let people set the environment on their own.
This issue should only affect old HW and old GPU drivers, anyway.
No, it can’t affect other users, because you’d be changing the environment for the application only if you set the variable programmatically.
Setting the environment variable programmatically before initialising GTK is actually the recommended best practice. Of course, it means using an older renderer everywhere, even on modern hardware, so that’s the actual trade-off you’d be making.