If I filter for kind 3 I'll get something like this:
[p 7cc328a08ddb2afdf9f9be77beff4c83489ff979721827d628a542f32a247c0e]] {"wss://eden.nostr.land":{"read":true,"write":true},...
It seems like the prefered relays just follow the "p" tags.
Discussion
Oh ya, if you're looking at kind 3 then that list is in the event content. Not the tag. But the p tag also has a relay in it optionally but it's not very reliable.
Yeah, I'm looking for my own relays in the event content, but I don't manage to get these into an array.
The content is an extra field, you probably have to json.Unmarshal it separately.