Explanation
A session security level is a setting that determines how secure a user's session is based on factors such as their login method, their IP address, their browser, or their device. Administrators can configure different session security levels for different user profiles and assign different actions or permissions to each session security level.
Multi-factor authentication (MFA) is a feature that requires users to verify their identity using two or more factors of authentication when they log in to Salesforce, such as their username and password plus a verification code or an app-generated token. MFA can enhance the security of user sessions and prevent unauthorized access.
If an administrator recently implemented MFA with a standard security level selected and is receiving cases that users are unable to log in, they should check the session security level required at login on the user profile.
This setting determines what session security level users need to have when they log in based on their profile.
If this setting is higher than the standard security level, users may not be able to log in with MFA alone and may need additional factors of authentication. References:
https://help.salesforce.com/s/articleView?id=sf.security_sessions.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.identity_mfa.htm&type=5

Explanation
Opening the flow in Debug mode and running it as another user allows simulating how the flow behaves for different users with different permissions and settings. This can help identify any issues related to user

Explanation
A lightning action is a type of quick action that can invoke a Lightning component, a Visualforce page, or a URL. The administrator can use a lightning action to redirect the user to a different page after they finish the screen flow. This way, the user will not see the initial screen again and will not misuse the flow tool.
References:
https://help.salesforce.com/s/articleView?id=sf.lightning_component_actions.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.flow_distribute_lex.htm&type=5

Explanation
Identity Verification History is a tool that tracks the verification methods used by users when they log in to Salesforce via multi-factor authentication. It can help identify any issues or errors related to verification methods such as email, phone, or app. Login History is a tool that tracks the login attempts and status of users who access Salesforce. It can help identify any issues or errors related to login credentials, IP addresses, browser types, or locations.

Explanation
The resume event is recalculated and the email goes out to the account owner immediately because the flow uses a scheduled path that evaluates the expiration date field every time it changes. When the expiration date is changed to yesterday, the flow resumes immediately and executes the action of sending the email