I like it.
But if they're not lists, what do you call them in the UI?

I used "Profile Lists" before and somehow "Categories" or "Labels" has a weird feel to it for people. Although that's obviously what you're doing: categorizing npubs with labels.
nostr:npub1fjqqy4a93z5zsjwsfxqhc2764kvykfdyttvldkkkdera8dr78vhsmmleku nostr:npub149p5act9a5qm9p47elp8w8h3wpwn2d7s2xecw2ygnrxqp4wgsklq9g722q is there a reason that would be silly?
I like it.
But if they're not lists, what do you call them in the UI?

I used "Profile Lists" before and somehow "Categories" or "Labels" has a weird feel to it for people. Although that's obviously what you're doing: categorizing npubs with labels.
They are a "list" in the UI. The client gathers the events together and builds a list for the display, just as it does with your followers, but with much less inconsistency because you regularly write to the same relays.
"followers" is a mess because the event is wherever _they_ write to, and you might not be reading from there.
I mean, you could actually keep all of these events on a private relay or use the private version of the events.

So like this'd be fine?
(I don't like lying 🙈 )
I like it. It's more intuitive because you could probably click on "271 Profiles" and see a list. You can't "see" a category. That's a descriptor, not a thing.
What this UI does is use your categories to produce lists at runtime. The categories can also be used to do completely other things, but here it's just building lists.
KWIM? Like, if you go here, you see the list of my followers. You do not see the "category" followers.
You categorize the npubs, in order to determine what will be included in the list displayed.
You also can do other things with the categorization, like batch-DM or batch-invite everyone under "best frens" or "community ABC", or have your personal algo shuffle the order of categories you see in your feed, or prioritize the order or change the formatting, according to category, or create custom feed DVMs, or etc.
Follow is binary follow/unfollow, whereas categories are circa 2000 possibilities, limited only by the size of the category event, and most clients will probably have some defaults, like "following" or "friends" or "contacts" or "must read" or "expert" or...