According to BET radio, the final straw was that Harry and Meghan had a huge fight, bad enough for the hotel management and security to be called in....after a deluge of complaints from other hotel guests......someone told Meghan to leave. My bet is that they were both threatened with ousting and Harry told her to leave.
The other IG games she attended, she usually left a couple of days before the closing ceremony, but this was a really early departure.