I guess that one disadvantage is that PR's are not a git feature, but a feature of the git provider, so you might get locked in with a provider, I think you can

I guess that one disadvantage is that PR's are not a git feature, but a feature of the git provider, so you might get locked in with a provider, I think you can export your PR history, but that means the provider where you are migrating needs to support also that feature.