OSM + GM indicate a D565 extension into Bandırma, i.e. to the harbour of Bandırma. It makes sense since there is another D565 segment north of the Sea of Marmara. 2023 GSV does not indicate any road number in the town but there is no GSV coverage of the D200 bypass where D565 branches off. I also failed to find videos.
The concurrent E90 has a "D565" wp to the west. However, I guess that panda80 simply missed to rename the wp when drafting the turd system.
https://travelmapping.net/hb/showroute.php?r=tur.d200&lat=40.346973&lon=27.966149&zoom=15Nonetheless, D200 lacks a wp for the grade-separated junction where D565 would branch off (and another GSJ to the south). Adding those wps (and renaming E90's D565 wp) but keeping the topic open till getting any confirmation on D565's extension into Bandırma.
Edit:
https://github.com/TravelMapping/HighwayData/pull/6917
