Instagram 6-digit authentication code

Hello, I had a problem on Instagram two weeks ago. I wanted to reset my password (which I have done), but when I completed this step, it then asked me for a 6-digit code from an authentication app, which had never happened before. The code in question is supposed to be received by email or phone, but nothing is being sent to me, and the codes I receive on Keychain or Authenticator do not work.

What is quite strange too is that usually I receive emails at a certain address, and this time I received them at another address of mine (which is over 10 years old) and that I had forgotten about.

If someone could please help me, this account is very important to me.

Thank you in advance :)