A Microsoft app for iOS and Android devices that enables authentication with two-factor verification, phone sign-in, and code generation
No one can prevent someone else from trying to access your account - you can only prevent them from succeeding, which you are doing.
You can always disable MFA in your Microsoft account. That will prevent the constant MFA requests, but it also makes your security much weaker.
A much better idea is to replace your password with a passkey. Anyone else trying access your account will get nowhere, so you won't get bothered.