I was looking around at my position in standings during systests and I noticed many of the low rated participants had nearly identical code for D2. Examples:
https://codeforces.me/contest/2002/submission/275809437
https://codeforces.me/contest/2002/submission/275816397
https://codeforces.me/contest/2002/submission/275809226
https://codeforces.me/contest/2002/submission/275826393
It seems like some high rated user leaked solutions of D2 and possibly E as well ([user:NikolaT] who has a clearly plagiarized D2 ac'ed E with weird variable names), and the cheaters have started reaching GM/IM perf.