At the end of April the TT went through a major change. For the next 4-6 weeks things fluctuated a bit. Now, it has settled back down to more normal, though the mix of puzzles still is weighted on the lower rated side.
https://www.chess.com/blog/News/chess-com-dev-update-april-28-2017
and
https://www.chess.com/blog/News/chess-com-dev-update-may-26-2017
TT changed about 2 months ago. Up till then I struggled to stay above 1600.
Now I am rated a ridiculous 1850.
Some of the individual puzzle ratings are insane e.g a simple recapture
was 2155 when I did it.