"Browser Intrusion Prevention is not functioning correctly" warning in Symantec Endpoint Protection / Endpoint Security client, when the installation of SEP Chrome extension is blocked.
This may occur in SEP/SES version 14.3 RU3 if the SEP Chrome extension is blocked. See blocking methods described at bottom of the following KB article: Installing the Endpoint Protection Chrome Browser Extension using an Active Directory Group Policy Object.
When the SEP Chrome extension is properly allowed, you should see a registry entry of the form
C:\ProgramData\Symantec\Symantec Endpoint Protection\14.3.5413.3000.105\Data\Definitions\WebExtDefs\20210809.038\updates.xml
There is currently no control over this error at the SEPM or SES management console or in client settings. You must either allow the installation of the SEP Chrome extension or remove the IPS component from SEP.
If you are managing the installation of Chrome extensions then make the appropriate adjustment to your Chrome extension management policy to allow the SEP Chrome extension. If you are deliberately blocking the SEP Chrome extension then this error is expected. Work-around would be to allow the extension installation but disable Browser IPS in SEP policy if you don't want to use it. Or work with Broadcom support if you believe there is a compatibility issue that requires completely blocking the SEP Chrome extension installation.