Python QGIS crashes within categorized renderer setup

Why does QGIS keep crashing?

Create a new, clean profile (under Settings / User Profiles ). You will lose and/or have to recreate certain default settings, but fairly often QGIS crashes are caused by something (internal to QGIS, a plugin?) corrupting your user profile.
 

How do I speed up PyQGIS?

Optimising your feature requests is one of the easiest ways to speed up your PyQGIS script! It’s worth spending some time looking over all your uses of getFeatures() to see whether you can cut down on what you’re requesting – the results can often be mind blowing!
 

What version of Python does QGIS use?

3.28 version at https://qgis.org/pyqgis/3.28.