What does the site mean with that "repopulated old tag" popup? At first I thought it referred to tags used by deleted posts, until a couple of times it popped up when I was tagging my own characters.

It means it dropped to 0 instances (of that tag), and you added it back. It's likely because of a common name that hasn't been disambiguated yet?
Maybe somebody accidentally used your characters' names on wrong post?
I'll look at tagging history to see.

:edit: Ah, I think I know what happened. That character was on a deleted post? Did you issue any takedowns? Is that one tag from your OC? Looks like only one of them has 1 instance, but I'm not familiar enough to know if it's likely that someone else drew it.

alphamule said:
It means it dropped to 0 instances (of that tag), and you added it back. It's likely because of a common name that hasn't been disambiguated yet?
Maybe somebody accidentally used your characters' names on wrong post?
I'll look at tagging history to see.

:edit: Ah, I think I know what happened. That character was on a deleted post? Did you issue any takedowns? Is that one tag from your OC? Looks like only one of them has 1 instance, but I'm not familiar enough to know if it's likely that someone else drew it.

This hasn't only happened once. I'd actually been meaning to ask about this for a while. Sometimes it happens with established characters and species, and an instance of that is what reminded me to finally get around to making the topic. But it has happened with my own creations before. (I don't entirely remember which, because I tend to upload months apart, but I know for a fact it has.)

I have never issued any takedowns, and I'm the only one who has ever uploaded my own characters. I'd just been assuming it was the generic message for adding *any* brand new tag with a category via the Edit function, but I'd just been confused about it.

You got this error because the tag was created and then removed from all posts, meaning that nothing was using this pre-existing tag when you added it in again. As anyone can add and remove tags, it's quite possible someone added it to one of your posts (or any post actually) before they or someone else turned around and removed it before you used it. It's just an informative pop-up, and can sometimes be useful to bring our attention to a typo or tag goof. If you made neither, then it's just a curiosity that you can just ignore.

I just did a little experiment. I got the popup even for

character:thisisatestaaaaaamxnsosmfjskskjd

. So yeah, it seems it's just a bug after all.

I messaged Earlopain about it, some time ago. He said it's a bug, he put it on the list.

I find it quite fascinating how many people on this thread have apparently never created a new tag before. This bug's been around for years, at least since the site relaunch.

wat8548 said:
I find it quite fascinating how many people on this thread have apparently never created a new tag before. This bug's been around for years, at least since the site relaunch.

I created the artist and character tag, for most of the time, by creating it first, and changing the category later. Either the bug doesn't show up this way, or I simply didn't realize it.

if you make a tag specifically with a prefix such as character: it will show up as repopulated. presumably that’s currently the only way the system knows how to give it the flair.

dubsthefox said:
I created the artist and character tag, for most of the time, by creating it first, and changing the category later. Either the bug doesn't show up this way, or I simply didn't realize it.

Same... Apparently it never happened to me, for same reason.

wat8548 said:
I find it quite fascinating how many people on this thread have apparently never created a new tag before. This bug's been around for years, at least since the site relaunch.

I created a new tag like a couple month after being here. Kind of shocked myself that not many others make new ones, I thought it was common since it’s tag what you see.

hardcore_zeraora said:
I created a new tag like a couple month after being here. Kind of shocked myself that not many others make new ones, I thought it was common since it’s tag what you see.

It's tag what you see, yes, but creating new tags should be done with care. The site's been around for over a decade with many many users, so the majority of useful tags have likely been thought up already. Doesn't mean there can't be new things, but what people can think up often are too generic to tag (e.g. eyes, white_sclera), and some things are too ambiguous (e.g. green, bush). You also want to make sure the tag is clearly communicating what it's for (separate from any wiki description) and that it isn't the same as or too similar to an existing tag (in name or function).