Steps to reproduce issue:

1. Open Qt Designer 6.5
2. Create a new Dialog
3. Add a QLabel widget and make it large (doesn't matter if its part of layout or not)
4. Under Properties -> Alignment, change Horizontal or Vertical alignment, but Text alignment doesn't change.

Here you you can see even the properties aren't updated properly in Designer.

Note: Manually editing the .ui file and re-opening it in Qt Designer shows correct text alignment. Also, Setting alignment works perfectly in Qt Designer 5.15.13, so its definitely a recent issue.