Start using alternatives to less secure apps as soon as possible.
•    Use apps that use OAuth 2.0 authentication. Update your existing apps to support OAuth 2.0 for authentication.
•    If some users can’t migrate to a more secure platform, they can use alternatives.

Less secure app     Alternative
Apple Mail configured with POP3    

Re-configure your Google Account to Apple Mail to use IMAP with OAuth2.

This automatically initiates the connection with OAuth2.

iOS Mail    
 

Continue using iOS Mail as long as you have iOS 6.0 or later.

OAuth2 support is automatically included in iOS 6.0 and later when you add an account using the Google option.

Outlook for Windows via password-based POP or IMAP

Google Workspace Sync for Microsoft Outlook (GWSMO).

Web-based or latest version of Outlook.

About Google Workspace Sync for Microsoft Outlook

Mozilla Thunderbird    
 

Re-configure your Google Account to Thunderbird to use IMAP with OAuth2.

This automatically initiates the connection with OAuth2.

Legacy office devices

Examples: scanners and multifunctional printers that send email

Continue using legacy office devices with SMTP. Other protocols (such as POP3 and IMAP) will be blocked unless they use OAuth.

Adding these to the MTA service is preferred.

   
Any other app     Request that the app developer update the app to use OAuth 2.0
If the app does not offer "Sign in with Google"    
 

Use App Passwords

Switch to a more secure app or device