Based on official FIDE classical ratings, not live.
If two players pass the threshold at the same update, will resolve based on who passed the threshold in live ratings first. If there is still a tie, then it will resolve based on which tied player has the higher rating.
Can resolve as someone currently rated 2800 or above in the event that they dip below 2800 in the official (non live) ratings and then passes it again in a later month.
Resolution date will be extended as needed.
Rating source: https://ratings.fide.com/
@DanielTilkin He was also over 2800 in the December list: https://ratings.fide.com/profile/35009192/chart
@JonathanNankivell Yes, I meant that he won't drop below 2800. So to get this, he still needs to drop below, then go above again.
@creator need to add Arjun to the list in the description it could resolve to. Probably to the list of answers as well.
@DanielTilkin note that cross has always meant exceed, hence the note in the description about Magnus etc being eligible if they go below and then back above. I'll rename the market