After adding Arbitrum from chainlist.org I noticed that the first networks were

https://arbitrum-mainnet.infura.io/v3/${INFURA_API_KEY}
https://arb-mainnet.g.alchemy.com/v2/${ALCHEMY_API_KEY}

It does list some other networks though.

This causes some people in community support to not work correctly.
https://community.brave.com/t/brave-wallet-not-allowing-0-gas-price-on-arbitrum-test-network/308777/13
https://community.brave.com/t/unable-to-send-eth-arbitrum-chain/317080/9

This one works:
https://arb1.arbitrum.io/rpc

Note it also adds one like this:
wss://arb1.arbitrum.io/ws

We should select the first reasonable URL instead (i.e. one without variables and one that is HTTP(S)) when possible.