Get data arguments

You are calling your model method incorrectly.
Your setParam method has two conflicting signatures - one with a single parameter and one with two. Neither of them expects an array, just values.
Your call to the method passes an array of parameters as the only parameter.
Read your error message!

I noticed this when browsing and if I take them like this:

PHP Code:

$model->setParam([
 'firstParam' => $this->request->getVar('firstParam')],[
 'secondParam' => $this->request->getVar('secondParam')
]); 


then they are transferred and not problem...

But I wanted to learn how to correctly pass multiple values in CI4, because I'm not experienced (

Thanks for the answer!