Does software renderer have any compatibility issues?

We switched our application from Qt 5 Qt Widget to Qt 6.3.1 QML with hardware renderer. Some of our users on VMs or very old HW (10+ years HW e.g., HD 3000 GPU) get transparent window (with non-transparent window border). In all cases, switching our application to software rendering fixes the problem. To avoid further issues, we want to switch the default renderer of our application to software renderer.

My question: Can switching our application to software renderer lead to regressions, or software renderer always safe from compatibility point of view?

Suggestion: Why Qt 6 is not using software renderer by default, or why it cannot fall back to software renderer when the HW rendering is not compatible for GPU?