Currently, the oracle checks the latest validator state (finalized) and uses it to decide if it can subscribe or not into the pool. For example, a slashed or exited validator can't subscribe into the pool.
However, the oracle should not use the latest finalized state, but the state of the validator when it was subscribed. Example: If validator v subscribes to the pool at slot s, the oracle should use the state of that validator at state s and not the latest finalized one.
This PR addresses that.
Low impact, only problematic when syncing from scratch.