I’m not sure that’s the case. Any country that blocks your end-user access to that server would also be blocking your local servers’ access to it too, after all its all just traffic to the firewall.
Edit: Oh I get it now. If your country blocks access to foreign site lemmy.abc, but not to foreign site lemmy.xyz, you can join .xyz and subscribe to content from .abc. It will be interesting to see how quickly the whole fediverse gets blocked by strict countries now...
I suspect though that any differences in content most of us are seeing between servers at the moment are down to the massive load that they’re under. Generally the federation functionality seems to be the most processor-intensive and fragile part of the setup. I've also been able to access posts on struggling servers using apps that the native web front-end isn't able to display.