Green arrow means you can download/upload. If its grey upload on e.g. paid relay nostr wine it means you have not paid for writing to the relay.
Other icons mean that you can set up only paid relays for universe feed.
Here is the amethyst relay redesign issue: https://github.com/vitorpamplona/amethyst/issues/96.
I brought this up with #[4]. Relay management is part of their hackathon: https://makers.bolt.fun/story/design-challenge-1-relay-management--596