The tag alias #75490 half_orc -> half-orc is pending approval.
Reason: For the sake of unification of interchangeable terms. Currently both tags are very low in count, but half-orc seems to be the more commonly used, and so it would be best to standardize on that formatting.
This does potentially cause issues when it comes to standardizing tagging half elves, as the formatting that is more popular in that case is reversed and it's best to be consistent. However, that is a separate discussion.