Not easy to tell from your images.
The glass is gripped into the riser mechanism with two clamps - one fore one aft. Black rubber pads (for obvious reasons), with clamp bolts/nuts. I don't think that's what I see in your images (but I am not sure).
You can see the black rubber clamp sections on this image from @EuropaSman (the nuts & bolts aren't in place in this pic). If the bolts aren't done up tightly enough, you can move the glass forwards and backwards.
Another potential culprit could be the rail adjusting screw, which varies the angle of the forward/rearward guide rail. This has the effect of dictating how forcefully the glass pushes into rubber seal at the top of the door aperture when the door is closed, in order to create a seal. Part no.6 on the deroure page that @21gg posted the link for.
If you adjust these without knowing what you are doing - they can fall out and end up rattling around at the bottom of your door. Ask me how I know. If they fall out then sitting in the drivers seat you can press gently and make the top of the glass move away from the seal.
They are easy enough to re-fit, but you need to turn them in the right direction - one end is standard thread, the other a reverse thread (so that when you turn it one way the gap between the adjuster blocks grows, and turning it the other way the gap closes).