What is 'Browser integrity check'?
The 'Browser integrity check' feature looks for HTTP headers abused most commonly by spammers and blocks access to your domain. It also challenges visitors without a user agent or with a non-standard user agent such as commonly used by abusive bots, crawlers, or visitors.
You can find this feature in the 'Application layer' section, which is located in 'Enhanced security' > 'DDoS protection'. The browser integrity check is enabled by default, you can also change the settings from 'Standard' to 'Strict.'
Standard vs strict
The only difference between 'Standard' and 'Strict' is, 'Strict' blocks more bots including search crawlers.