The AntiBot Detection Engine massively improves Shield's ability to identify bad bots vs all your other "good" traffic (humans + good bots). This is important because Shield can better detect bad bots and eliminate more bot traffic from your site, including comment SPAM, contact form SPAM, login/registration bots, and checkout bots.
Many 3rd party plugins provide custom user login, registration, and lost password forms. They aren't normally checked for Bots since they require a custom integration.
You can select your 3rd party providers to have Shield automatically detect Bot requests to these forms:
Important: Only the form types (login, registration, lost password), that you have selected in the Login Guard module will be checked: