This is a bug demo. Tested on Safari Version 14.0.3 (16610.4.3.1.4) macOS Big Sur 11.2.1.

Steps:

• Visit this page in Safari
• Resize the browser to a width between 800 and 1200px
• Mouse hover over the 'test element' text at the top of this page
• What happens: The text will shrink in size
• What should happen: The text should stay the same size

This bug has a bug report already.