I barely have time to test while currently using LGIS for business. My first impression and a first problem:
Great: the new styling rules are a long-awaited feature!
Unfortunately: the styling of text labels no longer works correctly in new layers: font color and font background are always set to 'black'.
The label color for existing layers remains as it was preset.
thank you for the bug report. You're right there is really problem with style for labels - we'll fix it.
the issue is fixed in the new version 1.21.1 (released yesterday). Please test it in the latest version and let us know in case of any problems.