Sorry to read you are having this issue.
Here is a “long shot”, “just to see” kinda thing, but it might lead you to some clues.
Consider temporarily “disabling tags” in your admin panel settings:
Then navigate to your tags page like before and refresh. You should get the standard Discourse 404 error:
- Oops! That page doesn’t exist or is private.
If you do not see the ’ Oops! That page doesn’t exist or is private’ message after you disable thread tags, that will be an interesting surprise; but I guess you will.
Then, go back into your admin settings and re-enable your thread tags, and refresh the tags page again.
I am guessing you will still see the “Something went wrong” message, but it is easy enough to disable and re-enable, and see if anything new or interesting appears which might be a clue.