After picking up my 2021 with 11k miles on it I would occasionally hear a rattling when I opened the trunk. I pulled back the the cover a little after hearing it one day and this screw fell out. I removed the cover to inspect closely and I do not see where it would go. The opening/closing of the trunk along with the spoiler are working just fine. I would need to remove the carbon fiber cover to look deeper into this but I see no reason to since everything is working.

A long shot I know, but does anyone have a clue on where this could have come from?