Transition clinker-plastic window

I believe the windproofing was achieved in our case more by window foam and finally by some kind of fabric tape (?).

It is about driving rain tightness on the outside - foam is not even airtight, inside a special fleece is used to create the airtight layer.

Silicone etc. has no place there anymore as far as I know.

Thank you all for the answers. I haven't done anything yet. In the meantime, I discovered a few other things on the house that could also be the source of the drafts. So I'll leave the windows as they are for now. Doesn't seem to be entirely wrong. Best regards Mika