Full details posted here: https://community.adobe.com/t5/InDesign/Paragraph-Styles-including-paragraph-border-and-paragraph/m-p/10741537#M162568

When I copy a paragraph style from another document, OR copy styled text, and then attempt to edit the paragraph style, elements related to paragraph borders and paragraph shading suddenly appear in the paragraph style. This happens even though paragraph borders and shading are turned OFF. I suppose it's not affecting the style, because it's not turning them on, but they style is overly cluttered and messy and is mucking up our shared group template.

I'm working primarily in CC2018, but also replicated the problem in CC2020.

I've tried a clean install of software, as well as deleting caches/prefs.