Standing water in spare compartment

[Robopfer]

I have a 2019 Atlas V6 SE (no sunroof). Had a flat and noticed standing water in the spare compartment. Dried it out good, but the next time it rained, the water returned. There is a 5-6 inch area on the ceiling where it meets the liftgate, that is wet, and some water droplets on the side wall where the water dripped. All the rubber moldings seem fine. Thinking maybe a leak at the weld where the roof meets the side panel? Or maybe where the luggage rack is bolted to the roof? Haven't figured out how to take the side panels off yet to investigate, wondering if anyone has any ideas? Saw some old posts but wondering if anyone has had this issue recently.

 

[Robopfer]

Update: Ran a bead of silicone along seam where roof meets side panel and around bracket where trunk lift support is mounted on right side. Targeted these areas because they matched up where the headliner was water stained. Still leaked, though not as much. Then ran a bead around rear roof rack mount, shark fin antenna, and brake light housing. Several rain showers later, no leaks. Thank you shadytheatlas, the shark fin antenna was likely the culprit...when I went to apply the silicone I could lift it up easily with my finger. Could be that when the vehicle was in motion the wind lifted the shark fin and let the water in.