FAMP and error with INPUT_POST variable

[weldlive]

I prepared a web server on FreeBSD 13.4: Apache 2.4, MySQL, PHP 8.1 plus many required modules for installing WordPress. The sample WordPress site launches very nicely, access to the admin panel also. After installing the Duplicator plugin, I get a critical error as:

Uncaught Error: Undefined constant "Duplicator_Libs_Snap_INPUT_POST"

I am not concerned with solving the plugin and WordPress problem. I'm just guessing that somewhere I didn't complete something in the server configuration. Does anyone have an idea what is missing? Thx!