The 1.17 snapshots seem to replace TagManager to make it more flexible, which might open up the possibility to allow devs to make their own tag groups without too much fuss. I've toyed around with it a little, but so far I've been unsuccessful. Running this (without actually adding any required tags) crashes the game on starting a world:
RequiredTagListRegistry.register(FOO_REGISTRY_KEY, "tags/foo");

Refer to #1467 (comment).

@joshyrobot mind post a crash report for that?