Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
If you have changed your email address on Google, that's for Google. It's completely different system. Your credentials for Microsoft services stayed the same. If you want to change login email address for Microsoft account, you can do it here: https://account.live.com/names/manage . However, there could be a problem with verification email, because it will be sent to your old gmail address. Please be careful with changes.
If you have perpetual Office (it's not Microsoft 365, that's subscription) it should be connected to your Microsoft account. You should see it here: https://account.microsoft.com/services