Call to undefined function create_function() – PHP 8.2

You are going to want to edit this line:

add_action( 'plugins_loaded', create_function( '', 'global $BBCode; $BBCode = new BBCode();' ) );

You will want to make yourself an actual function. Probably something like this:

function my_hacked_function(){
    global $BBCode; 
    $BBCode = new BBCode();
}
add_action( 'plugins_loaded', 'my_hacked_function');

I’ve not tested this. However, this is the general direction you will want to go.