I have opened a tip for a community member who mistakenly sent 10.18 DOT directly to nomination pool 61 instead of using the nominationPools.join extrinsic. By this action and given that no one holds the private key for the destination account, the user is now unable to access funds. Considering that the balances.forceTransfer call is very powerful and it takes a more complex process, and the balance is low, I think the best option is to refund this community member through a tip. If you know any other solution, we are open to listen to you.
You can find the references below:
Rewards address of the pool 61
Transaction to the pool rewards address
A similar event happened in the past and is being taken as a reference. You can see it here.