The entire Extra Fields section is gone from the Advanced Edit Mode, I see.
You could right now add it with [cred_field field='recaptcha' class='form-control' output='bootstrap'], manually, but usually, you would add it in the "Add Fields" GUI when editing the Form in Expert Mode.
This must have happened somewhere in the updates where the new Block Editing mode was introduced, as in 2.0.1 this still works fine.
I'll let you know once I have an erratum with an eventual solution other than manually inserting the Field.
For other captchas but Google, you'd have to apply custom programming that we cannot support.
Unfortunately there is no API that lets you replace reCaptcha with something else in Forms, however, you can do any validation action with Toolset Forms API: https://toolset.com/documentation/programmer-reference/cred-api/
Other than that only the Google reCaptcha is included.
This is a quick update to say that this minor issue was finally resolved in the latest Forms release.
If you don't see an update notice on your plugins page, click the registered link for one of the Toolset plugins to take you to the custom Toolset installer page, and use the Check for Updates button, otherwise you can download the latest versions from your downloads page at toolset.com/account/downloads.
