Water Collecting in Boot Door

Good Morning,

I am a relatively new owner of a 2018 Grand C4. I am pretty happy with the car, despite few quirks... it is a Citroen, so quirks are expected.

I have noticed that after a good rain, about 1 litre or so of water comes pouring out of the boot door when I open it up. It comes out along the edges of the side. I am concerned about long term rust issues here... Has anyone seen this before? Any possible fixes, besides going to the garage?

Thanks!

Dan