A recent change to cohost prevents tagged shares of a post to show up under any tag pages, this was done to "reduce the risk of harassment from someone sharing a post, adding tags, and thereby causing it to appear in tag searches that the OP didn’t want it to appear in."
I agree with the reasoning behind this change, but it doesn't make much sense if OP is the one adding new tags. For example:
With the above use cases (and ideas from other request topics) in mind, the original poster should be allowed to reshare their old posts to new tags and have them be discoverable in the tag search pages, under the following criteria:
Relevant Topics for Reference:
"Allow the author of a post to..." (author repealed this feature request, but the feedback they received could be valuable to consider): https://help.antisoftware.club/support/discussions/topics/62000183243