Kayne mentioned something about seeing less comments when he's on primal compared to yakihonne or amethyst.
Him and a few others were accusing amethyst of bringing in shadow bans (if 5 people you follow have someone muted that you don't already follow their account is hidden from you)
The solution is to use different clients.
Client side censorship is a risk but anyone can build on nostr.
Same with relays, the bigger corporate relays are going to have a lot of censorship as Nostr gets more popular.