I noticed some paricipants commenting "Where is my problem X?" and feedbacks like this blog after Codeforces Round 921 (Div. 2) finished system test. Then I investigated their submissions during the contest, and finding their last "Pretest passed" submissions remain untested by main tests AFTER the contest.

More such submissions can be seen by filtering all "Accepted" submissions during the contest and sorting by judging time.

Is there any reason for this?

UPD: It seems to be fixed.