What caused the crater on the Yamal peninsula?

[D H]

Just browsed the Yamal on Google Earth --- "dozens?" --- there are thousands --- not all recent, certainly.

I suspect you are mistaking the thousands of permafrost melt ponds that occur all across the north for those newly formed craters. For a striking example of the thousands of lakes in the far north, see this map https://www.google.com/maps/place/69°36'00.0"N+132°00'00.0"W/@69.6,-132,8z/ of the Tuktoyaktuk Peninsula, in the Canadian Northwest Territories.