It’s not Voyager’s fault, Lemmy has always promoted dead and abandoned communties as “trending”. The grouping is useless and can always be safely ignored.

On desktop, I use an ad blocker to hide the div.

It might just be new communities.

Lemmy World does the same, if you look at ‘Trending communities’ section (as desktop view), they are new communities.

Not sure about the top and bottom ones, but I’m pretty sure those @a.gup.pe ones are Mastodon “groups”. They’re a reflector that you tag into a post to have it shared to its followers across all instances, rather than just your local instance (as with hashtags).

They’re a workaround for one of the limitations in Mastodon, but they work. I expect they’d appear empty if viewed in Lemmy.

More info here: https://fedi.tips/how-to-use-groups-on-the-fediverse/