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?
There’s no shadow bans. It’s possible that you’re interacting with an instance that has defederated from your home instance or vice versa. You won’t be told this. Everything just appears empty. Same if you’re banned from a community/instance. You won’t be told this unless the moderators message you.
Since I can see their content just fine it doesn’t appear to be defederation. But if they did ban me and there is no way for me to know, isn’t that a shadow ban?
What’s the instance and community you’re having problems with and I’ll tell you what’s going on. You would know you were banned by viewing your profile on that instance. You can find reasons in the modlog too if they added any.