OK, so, Kumo Desu Ga Nani Ka?, if you haven't looked at it yet (I heavily recommend the light novels and manga and just as strongly recommend you avoid the trash anime...), involves a mystery as to the identity of its main character. The main character starts off as the nameless (fan-named) Kumoko, a cutesy white spider. Her true identity is hidden with several misdirections and red herrings (even her gender is originally not confirmed), and a significant amount of the story drops clues to her identity. (In fact, for the anime, it's only revealed at the end of the very last episode that has aired.)
Because of this, even if they have been tagged as spoilers in the past, putting the tag for Kumoko, the original spider character, on the character she eventually becomes, Shiraori is a massive spoiler in and of itself that is completely pointless and also winds up making about 80% of the posts from Kumo Desu Ga wind up with the Spoilers tag. The characters have different names, entirely different appearances, and even in the Kumo Desu Ga wiki have different wiki pages. The only reason I can see that both character tags are together when there is only one character in the image so far is that the spoiler-ific Pixiv tagging system was doing so.
Since it is such a needless risk of spoiling users, most of whom likely only know the series from the anime (which again, explicitly shows the two characters in different contexts and their being the same person is a spoiler only revealed in the last episode), I don't see a reason they should both be tagged on posts where there is not a spider in the image. I'm going ahead and separating out the tags and also added a note on the character tag wikis on this page, but wanted to put notice why this is being done.