As of Git 2.20 you need to explicitly specify the force flag:
git fetch origin --tags --force
Until Git version 2.20, and unlike when pushing with git-push[1], any updates to refs/tags/* would be accepted without + in the refspec (or –force). When fetching, we promiscuously considered all tag updates from a remote to be forced fetches. Since Git version 2.20, fetching to update refs/tags/* works the same way as when pushing. I.e. any updates will be rejected without + in the refspec (or –force).
https://git-scm.com/docs/git-fetch