I have a very similar issue where I enter my (correct) password, Google recognizes it but says they need some additional verification where they require one of

I have a very similar issue where I enter my (correct) password, Google recognizes it but says they need some additional verification where they require one of my previous passwords to be entered. I don't know my previous password, so I am locked out of my account. What's funny is I have another account to which the Gmail of the said locked account is connected, so I can send and receive emails by the locked account, but I cannot use it for any other purpose. It has been the trigger due to which I had switched my primary email to my own personal domain and a better service provider for a few bucks a month. It's painful and I'm still in progress of transferring all communications to the new domain, however it's totally worth it because I have a sense of actual control.