Pixelated (i.e. no antialiasing) QML items in screenshots taken when running spix in github workflow

[nirvn]

When running spix as part of a github workflow using their ubuntu-20.04 container, images taken from the takeScreenshot show pixelated QML items.

E.g., the top image here is how spix captures the QML scene is rendered locally, while the bottom image is how spix captured the scene during an automated github workflow:

Nice antialiasing on tool buttons

Pixelated tool buttons

The workflow is here (https://github.com/opengisch/QField/blob/master/.github/workflows/linux.yml). Is there a flag somewhere in need of being switched on for antialiasing to work properly in this context?