Last night at 11:55 PM Eastern, Subeta was throwing 504 errors while I happened to be questing. I tried twice to submit the items for the Drunk Carl quest that I was in the middle of. It never accepted the items, however they disappeared from my account. Fortunately, they were cheap, but still...

Yes, I think so. My concern was that the lag somehow swallowed 3 items from my account without ever finalizing the quest. My items were inexpensive, but there might have been other people affected who could have been doing Sagittarius or Item Hunt and they might have lost something significant.