I lost one of my accounts last month to something similar to this. I used to have a secondary email as 2FA and then it got changed to "use one of my active devices", honestly I don't remember if there was some popup asking me to confirm the change, but one day I changed my iOS devices and the account was lost for good as I could not "tap confirm".
I tried to contact them from the email that used to be the 2FA, but no one could help me. It was a sad and eye-opening experience as I could have lost google domains and more.