20 Compute Units and each notification delivered on the subscription will use 10 Compute Units regardless of size.
Reference: Here
Parameters
subscription type- string - The type of event you want to subscribe to (e.g. newHeads). For Monad, this method supports the following subscription types:
data - object -(Optional) - Arguments such as an address, multiple addresses, and topics. Note, only logs that are created from these addresses or match the specified topics will return logs.
Returns
result - string - Hex encoded subscription ID. This ID will be attached to all received events and can also be used to cancel the subscription using eth_unsubscribe.