Why is multi-factor authentication not working?

https://quicklybookonline.com/blog/quickbooks-multi-factor-authentication-problems/

Multi-factor authentication has become one of the most effective ways to secure online accounts. Instead of relying only on a password, it requires an additional verification method, such as a code sent to your mobile device, a notification in an authentication application, a security key, or biometric verification. This extra layer of security helps protect sensitive information, even if your password becomes compromised.