It seems like Halloween should be a general tag instead of a copyright.

Halloween is owned and operated by Party City and Hallmark.
Lolz, I don't know, probably general.

Last I heard, it was decided that all of the holidays should be copyright tags. (discussion here: forum #135132).

Like other copyright tags, holiday tags are as much crediting what something is from or part of specifically. Things tagged with holiday tags tend to be stuff that pays homage to several combined characteristics commonly and easily recognised as being associated with that holiday. (the themes, the iconography, the traditions, the mythos, the merchandise, and iconic color combinations, etc). It's almost like each holiday is a miniature fandom with its own fanart. People recognise where it's from and tag it with the holiday tag that it's obviously referencing in multiple ways...and that's very similar to how normal fandom art is recognised where it's from, and then tagged with the appropriate copyright tag so that it's searchable. It's not the same as more general tags like brown_hair, where it's not really "from" anywhere and is simply just a single trait that's seen within the image.

There was also the feeling that with how commercialised most holidays are, having them as copyright tags instead of general tags seemed to be appropriate. And it's been noticed that the holiday tags tend to get overlooked and forgotten when they've spent time as general tags. But tend to be tagged more often when appropriate whenever they've been copyright tags, making the results more useful to everybody searching with them. And they do get searched a lot regardless, especially during a holiday's calendar season.

Well, that answers that question. Glad I asked before changing it. Good reasoning too.