So, have you ever had a situation where you accidentally pushed the wrong tag to your remote repository and need to undo this?

You can first delete the tag on your local copy.

git tag -d TAGNAME

Then push the tag to the remote repository.

git push origin :refs/tags/TAGNAME

Create the tag again on your local copy

git tag -a TAGNAME -m 'same tag name, new commit'

Then push the new tag to your remote repository.

git push origin TAGNAME

Further Reading https://git-scm.com/docs/git-tag