rattle noise

Hello Frederickdawg, I was underneath my 2021 prius prime and took out the bottom panel to see this piece. as I am having major rattle noise at 33K. I figure that it is not the suspension or steering as I have no clicking sound, but rattle noise on any raod, but more prominent in uneven road. I did take out the panel piece but the rattle noise was still there. What type of fabric did not used to wedge the gap? Did you put it between the panel piece and the vent? Thank you in advance

Can you clarify where you put that fabric and what kind of material you used? Thank you in advance.