I noticed a gap in the seal of my sunroof. Not sure if it has been there all the time.
Why this small gap? Is there a small part missing here?

 

It seems that Volvo used some material that it doesn't work well with heat.

If the car is under warranty you can try Volvo and ask them to replace it. I have seen some full seals up for sale on ebay that may do the trick like full seal replacement. I have also seen few pots on redit that someone had their seal replaced 2x and the same thing happen. This may help to solve your problem. Sort of easy and cheap fix.

https://poormansupercar.com/shop/car...-xc60-v60-v90/

https://www.ebay.co.uk/itm/365032666319

There is also someone in Canada that does those kits:

https://fnfdesign.ca/products/volvo-...ink-gap-filler

This is crazy that new cars like this have simple issues like this. It is worth double checking with Volvo if they will fix this under warranty.

What sort of gaps does other people have?