Version strategy for backend/frontend

When self hosting without docker, I have added the two required repos as git submodules in my "container" git repos. I then wondered what versions work together - hopefully master and master (what I'm using now, but hopefully not in the future ;-), but otherwise, version numbers look different? backend is at 1.9.0, whereas frontend is at 1.12.2 (looking at git tags).

I guess tags got lost on backend? When updating the submodules, it is nice to be able to just pick a tag with the same name, like "v1.12.1", and update both submodules.