Oh. nostr:npub1xtscya34g58tk0z605fvr788k263gsu6cy9x0mhnm87echrgufzsevkk5s also told me that this is too many people and Nostr doesn't like contact lists this large. ¯\_(ツ)_/¯
Discussion
Clients can send pubkey prefixes, so even if you have huge follows lists (to a degree) this can be mitigated
It was fine up to 2000, after that stuff gets wonky.