I noticed something strange where an artist has the number 2 next to their name but only 1 post shows up

The other image likely got removed.
Removed images still show up in the tag count because they're still in the database, but hidden essentially.
(If I remember correctly, it's so that images can be restored if somebody makes a good case to have it restored.)

Either that or the image contains a tag that's in your blacklist, and it's being hidden from searches as a result.

The artist is sheepupy please could you help me check if it was deleted

Seems like it was removed, because I'm only seeing 1 image tied to that artist tag whenever I search it.

You can always check their social media accounts if you really want to find their art online, or alternatively you can Google their various artist names.

Here's their Twitter/X:
x.com/Sheepuppy1

I can't even see it, whatever it was, its gone gone, the number just hasn't caught up.

Changed sheepuppy to lost-tyrant

the name should be sheepuppy, lost-tyrant is their SFW

Danbooru has sheepuppy listed as an alias for lost-tyrant.