I tried to use the Relay email address to login to aarp.org since I needed to renew my membership and thought I’d give Relay a try.
I couldn’t use the Relay email to login to my existing aarp account - I’d get errors and couldn’t log in.
Did you have the Firefox Private Relay address set as the email address or login credential for that account?
It was the login credential. After login failed, I reset my password but they couldn’t find an email address matching the relay one.