I'm sort of stuck on a merge there. I have not figured out a reasonable way to have bzlmod ignore the compatibility level loop between ***@***.*** depending (transitively) on rules_proto, where all versions depend on rules_pkg at level 1. Updating rules_proto is obviously wrong in 2 ways. It can't work until rules_pkg is already added. It puts the change burden in the wrong repo. Doing a special MODULE.bazel that hard specified rules_proto might work. But that feels wrong too. I don't care what version of proto you get. User workspace should win, followed by tools I depend directly on. It is also tedious, because the bcr tests make sure the module.bazel inside the tarball and given are identical. Which means a dummy release of rules_pkg for each test. That is ugly. I filed bugs about the difficulty of updating a compatibilty level for any widely used module. I just ran out of time to beat my head against something that is probably better fixed with a bazel flag to not care about version conflicts and a fix to the bcr submit process.

That may be the path of least resistance. I don't have the time to figure out a general solution to the transitive loop problem. I'll send a PR