Morocco: Weird significant drop in rate Revolut has given me

I have been withdrawing from ATMs in Morocco over the last ten days without a problem, all transactions have offered between 12.30 and 12.49 MAD per GBP, except one. This transaction was on 21/06/17 at 22:26, and I have been given £1 = MAD12.0475. The ATM transaction previous to this was on the same day at 18:02, and I got 12.35. The transaction after this was 22/06/17 at 08:29 and I got 12.34.

Why the sudden drop to 12.04 on this transaction at 21/06/17 at 22:26 ? I have checked the XE graphs and there are no spikes downward on said day.

Could someone at Revolut clarify please?

Two thoughts: XE shows mid market rates. (Revolut uses live interbank spot rates with a spread between bid/offer). And seconds: the market is always in flux. Graphs on XE don’t show this in detail, partly because they are showing mid market rates.