Thanks for the report @Don! It looks like the reactions/follow plugins originally copy/pasted the HTML structure from core, and so they were both depending on the old CSS.
I think we can make things cleaner by re-using core’s <UserStreamItem> component in both plugins:
This will add a bit of extra core customizability: DEV: Add `{{yield}}` to user-stream-item for plugins/themes by davidtaylorhq · Pull Request #20791 · discourse/discourse · GitHub
Fix for reactions: UX: Re-use UserStreamItem from core by davidtaylorhq · Pull Request #217 · discourse/discourse-reactions · GitHub
Fix for follow: UX: Re-use UserStreamItem from core by davidtaylorhq · Pull Request #91 · discourse/discourse-follow · GitHub