– Facebook's pixel will, by default, attach click listeners to the page and send back associated metadata. This simplifies implementation needs, but can create unintentional information leaks in privileged contexts. To disable this behavior, there's a flag[1] you can use. After which, you can manually trigger FB Pixel hits and control both when they're fired and what information is included in them.
– There's a feature for the FB Pixel called Advanced Matching[2] that allows you to send hashed PII as parameters with your FB events. "Automatic Advanced Matching" can be enabled at any time via a toggle in the FB interface. I believe that setting autoConfig to false as mentioned above will similarly prevent Automatic Advanced Matching from working (since it disables the auto-creation of all those listeners to begin with). When manually triggering pixel calls like above, you can use this functionality via "Manual Advanced Matching"[3].
As a general rule, I'd strongly encourage anyone implementing a Facebook pixel to also include the autoConfig = false flag. This makes it work like most other pixels, where the base tag just instantiates an object. After which, hits only occur when explicitly defined in the site code, and include specifically what details you include in it. That way you're fully aware of the scope of data disclosure happening and any need from marketing to include sensitive (or potentially sensitive) information in these calls has to be explicitly requested (and theoretically vetted) as part of the standard dev process.
[1] https://developers.facebook.com/docs/facebook-pixel/advanced...
[2] https://www.facebook.com/business/help/611774685654668
[3] https://developers.facebook.com/docs/facebook-pixel/advanced...