For any tag on Cohost there is only one Canonical Capitalisation but each possible variation has its own (empty) tag page. e.g. https://cohost.org/rc/tagged/abba has results but https://cohost.org/rc/tagged/ABBA does not. This comes up most when searching users pages for tags, which currently has to be done by hand, but it would be handy anyway. Not sure if this should be a feature request.
I believe this also affects filtered tags/tag muffling. I have a specific tag I wanted to mute and I noted it appeared in the tag search with different capitalization, and I was able to add both versions.