Rocket Pool rETH and Coinbase cbETH as proof of funds
You staked ETH through Rocket Pool or Coinbase and now hold rETH or cbETH. The token count is lower than the ETH you started with and it never changes, yet the position is worth more ETH every day. That confuses most proof-of-funds checks. RealOpen converts both tokens to ETH at each protocol’s own on-chain rate and counts them at the ETH rate.
Neither token needs unstaking to verify, to get a letter, or to close. You need the address that holds it, and about ten minutes.