It appears that a community manager has now blacklisted artificial-intelligence. Questions that only had that tag are now untagged. (The version without the hyphen, artificialintelligence, is blocked too.)
Stack Exchange sites have a mechanism called "intrinsic tag blacklisting" that's intended to do exactly this - prevent the tag that simply describes the topic from being used.
However, the way the system works means that it doesn't always work. The system takes the URL slug before .stackexchange.com, and blacklists that as an intrinsic tag. For this site, ...
As mentioned in the MSE question linked in the comments, that indicator isn't calculated just for you. When you gain the "access moderator tools" privilege - 10K on graduated sites, 2K in public beta, 1K in private beta - you always see the total number of reviews pending for anyone. That is, even if the queues look empty to you (i.e. you reviewed each item ...
As mentioned by Rory Alsop, you've run into this Stack Exchange bug or something related. You can manually fix your profile by editing it on this site, or by opening your profile settings on a different site and choosing Save and copy changes to all Stack Exchange communities.
This is status-bydesign, although it is not because of the private beta.
From List of all badges with full descriptions:
A tag must appear on a minimum of 100 questions to be considered for tag badges.
Since we don't have tags with 100 questions or more, we don't yet see tag badges.
Likely it's going to be a while. I emailed the "powers that be", noting that we're starting to get traction and that we have a prestigious sponsor, but no reply as yet. I'll ping them again after the New Year and update my answer as I get more information.
No, this is not the reason. The reason is that you create posts whose content is off-topic. Please, see our on-topic page. Please, read it very carefully (especially, the notes)! If something is unclear there, please, let me know or ask another meta-question.
This issue has been discussed several times in the past. AFAIK, initially, this site wasn't meant to accept machine learning, statistics and programming questions (because that's already covered by other sites), but machine learning questions have been asked on this site for a long time and, given that they are considered part of AI, they are certainly ...