Ethereum staking rewards earned by Interactive Brokers clients are credited as additional staked cryptocurrency balance to their accounts.

From the articleInteractive Brokers launches Ethereum staking as crypto push expandsAlso in Interactive Brokers adds Ethereum staking as $900B broker expands crypto, Interactive Brokers expands crypto services with Ethereum staking via Zerohash, Interactive Brokers Rolls out Ether Staking With Zerohash