tactics trainer rating dropped


They made a number of adjustments in May. One fix allowed big jumps. Your rating went up in May by a lot. Looks like you are just getting readjusted.
See one of the numerous threads on this.

I went about 100 points down too this days! It is crazy. I'm solving much more problems than I fail, and still going down in rating. It is going crazy. I get one point for solving, unless I solve it in 7 seconds. Then I fail one and lose 15 points!

It's possible that you would learn something by reading:
https://www.chess.com/forum/view/general/what-s-up-with-tactics-trainer