Yes. Just like I always can run my own relay and my own client, clients can hide my content.
I'm talking theoretically, not saying it's happening.
How to do it is easy: just set a condition not to display post from npub.
There is no solution, not your client not your decision.
Setting up a relay and client is cost prohibitive and won't ever work for everyone. Unlike Bitcoin, Nostr is a social network. It doesn't matter if you can or can't be banned. What matters is your followers seeing your shit.
Nostr isn't p2p, it's p2many