What does one need to do to have Checkbox (BIT) values go lower case for use in Web connector body?

Struggling a lot to get a Web connector call to work, even though it gave a 201 response status code.

We have a Checkbox with a BIT data type in use and have this value used in the body of a call. In this example to set the two factor authentication type to “Password and TOTP token” and if one want to enable/disable “Allow fallback to em-mail”.

It turns out that the boolean value is starting with a capital letter (True):

{ "two_factor_authentication_type": 3, "allow_fallback_to_email": True }

After a test with setting the body value manually and not through a flow parameter it does actually change the requested data when it is lower case (true):

{ "two_factor_authentication_type": 3, "allow_fallback_to_email": true }

What do I need to do to have the parameter not be starting with a capital letter?