I noticed that some instances seem to sort of shadowban users from what I presume is any instance not on a whitelist.

This might sound like it might be regular defederation at first, but I can see or interact with their content just fine from my all feed while anytime I attempt to interact with communities on there in any way literally nothing happens, as if my contribution were invisible.

No replies, up or downvotes, no deletion or ban. Just shouting into the void while everyone around you (from that or other whitelisted instances) is having lively discussion.

Granted there is also the possibility that my contributions were uninteresting but my general experience is that people love to argue, or at least downvote whom they disagree with.

Is this a thing I should be aware of? That some federated instances have unilateral shadowbans in place?