Sending, receiving, and organizing email in Outlook.com
Hello,
According to the Microsoft Account activity policy, if you remove all of your previous security information and replace it with something new, your account will be put into a restricted state for 30 days.
"Before doing that I sent a message to change one of my security settings so that I will always have access to 2FA anywhere in the world." --
It appears that you removed the phone number associated with your Microsoft account and replaced it with a new one. If two-factor authentication (2FA) is enabled, you cannot sign in using only your password. You also need to verify your identity using a second authentication method. In your account, the only verification method was the phone number you removed or replaced; your account will remain restricted for 30 days.
During this 30-day period, you will be not able to sign in to websites or services that require your security information. However, you can continue to send and receive emails if you are already signed in to your Microsoft account through Outlook or other Office apps on another device.
Note: Microsoft always recommends that account users have at least three verification methods active. So, even if one method isn't working or is disabled, you can sign in with another verification method. So, even after 30 days you get access to your account, make sure you go to the security settings page of your Microsoft account first and add three verification methods.
Reference:
What does “Security info change is still pending” mean?
Let me know if you still need more help.