This is a bracket designed to help secure a portion of a roof shade for a Tesla Model 3.

This, and it seems most, roof shades designed for the Tesla Model 3 come in two parts. One for the roof window over the front passengers, and one for the rear passengers. The one for the rear passengers only secures on three sides though, since there is no crossbar for the rear section to attach to; just glass. This causes the back portion of the rear shade to droop down, blocking some of the driver's vision through the rear view mirror.

This bracket solves that problem. It attaches to the window by means of a double-sided suction cup. One half of the cup slips into the bracket and the other attaches to the window. The tab from the shade then slips into the slot on the bracket.

I just printed and installed two of them today on my shade. It's holding fine so far, but who knows if the suction cups will hold forever. Perhaps double-sided foam tape would be an option if the suctions cups fail.
(Note that the photo with the suction cup is an older version.)

Roof Shade
https://www.amazon.com/dp/B092VB8RWW

Suction Cups (20mm)
https://www.amazon.com/Double-Sided-Suction-Transparent-Non-Slip-Bathroom/dp/B0DD6XPF9D