As long as a user is still at a paying level, I can find them in the USERS section by doing a search for their PayPal subscription ID.
But once they EOT, their subscription ID field gets deleted automatically, and if their WordPress account email address is not the same as their PayPal email, I have no way of finding them.
This typically happens when I receive a Subscription cancelled email from PayPal, and the cancellation was on the same day as the downgrade.
I think the PayPal subscription ID should continue to be stored somewhere, where the USERS search function looks. Right now it’s stored under the Administrative notes section on each downgraded user’s page, but the User search function doesn’t look there.