They read the relays. Then store everything, but they can choose what to censor or not. They only show you portions of what you or others note.
Discussion
I should clarify. They can “choose” to only show you portions of what you or others note.
I have also read on here that primal app doesn't function when you disconnect from their server. Even when connected to other relays
Tbh it is a bit unfortunate but I understand; its a great way to bootstrap the network for a new user to feel like a more traditional social media. They'll find their way to other nostr clients as they see fit, with the power of their npub
Any relay can choose what to show you and what not to show you.
That’s fair. But they are knowingly censoring content.
Which content are they censoring?
Question would be if, in addition to withholding notes they can also tamper with
Since each note is signed by your nsec. I’m fairly sure they can’t modify. They can and have censored people’s notes. Selected not to show a given note or not allow some things in search.
🙄
That probably depends if their clients validate the signatures properly. Check the source code.