I found unknown parts in the bottom of the door

Hello,
I have a P2 (2006). I need your help to identify two parts. Recently the left front window regulator broke down. I took it apart, fixed it, put it back together, and it works, so there is nothing wrong with that part. However, at the bottom of the door, I found a rubber part and a socket nut that I don't know where they belong (they were there when I started the operation).

Does anyone have any guesses as to which part of the door they are missing?

(The 100HUF is just for proportions (23.8mm diameter). The vapour barrier film was still intact, so I think I took it apart first.)