Missing Authenticator backup and lost access to linked accounts after changing Apple ID

Hi, I changed my Apple ID email from <Mod remove PII> @gmail.com to <Mod remove PII> @icloud.com, and now my Microsoft Authenticator app no longer shows the “Cloud backup” option or any of my older linked accounts.

Previously, my Authenticator was connected to several accounts including work, school, and some personal logins like Instagram (used for two-factor authentication). After changing my Apple ID and reinstalling the app, I only see a few accounts and no “Backup” option at all.

I’m not sure which Microsoft or Gmail account my old Authenticator backup was tied to, but I need help identifying whether that backup still exists and if it can be restored to my current device.

Is there a way for Microsoft to check if my old backup (possibly under <Mod remove PII> @gmail.com) still contains the Instagram 2FA entry or other linked accounts?

Thank you for your help.