You can be de-platformed using the Amethyst app
Discussion
Yes but that's something built on top. You cannot be deplatformed on Nostr itself.
And as far as I know, nothing prevents other clients from implementing the same default in the future unfortunately, so there's work to be done and hopefully we'll see a lot more clients by then.
The biggest nostr client on Android shadow-banning users by default is de-platforming.