Gmail Account Recovery Blocked by OTP Sent to Old Phone

I have been unable to access my original main Gmail account on my Android mobile phone for about six months. Whenever I try to log in, Gmail asks to send an OTP to a phone that I used in the past, but I no longer have that old mobile phone with me. Because of this, I cannot enter the OTP and my Gmail does not open at all. I have already tried all the basic solutions such as restarting the phone, updating and reinstalling the Gmail app, and clearing the app cache, but the problem remains the same every time. I also tried to get help from Google support, but I have not received any useful reply or clear solution so far. This Gmail account is my original ID and it is very important for me. I kindly request that my Gmail account be recovered and that, instead of sending the OTP to my old phone, you send the OTP to my friend’s Gmail address “Mita****[email protected]” or provide another suitable verification method, so that I can access my account again.