Question about the first debate with Aviv

You've probably been asked and answered this many times before, but I didn't find exactly what I'm asking. In the first debate with Aviv Franco regarding the argument for the existence of God from the existence of the world based on the principle of causality. On the one hand, you said that because the principle of causality is a product of reason and not a conclusion from experience, it is not reasonable to reduce it only to things in our experience, and therefore it is reasonable to assume that the existence of the entire universe also has a reason, even though the entire universe is beyond our experience. On the other hand, you said that in order to stop the causal chain, there must be an object where the regression stops and it is an object whose existence does not require a cause and to which the principle of causality does not apply because it is (very, very) beyond our experience. So I didn't understand here – if in your opinion the entire universe is like things in our experience (a clock, a tree, a mountain), then why did you use the argument that causality is a product of reason. And if the entire universe is not like things in our experience, then it must be the one that stops the regression.