The following never happened before November 2021 update. Afther the update, while I'm working with a report page, some text elements randomly (e.g. when another visual selected) changes visible font...
I have the same issue. X and Y axis font sizes jump up and down in card visual (callout value font size), line chart and clustered column chart visual.
This behavior came with November 2021 update and I'm seeing it in the published reports as well. Prior to the November update there were no "jumping" of font sizes.