Matt J. I can't share my current project, but in a nutshell, it's the issue that if you use a font variable in Webflow on a Relume class (e.g. on .heading-style-h1) and then paste a Relume component using the same class, it creates a duplicate class on paste.
Looking through the support forums, it's been identified as a bug a few times last year, but there's no mention of a resolution yet.