Why is the mempool clearing?

Over the past week the mempool has dropped from 220 to 70 vMB after a long period of being well over 100. JoHoe's chart https://jochen-hoenicke.de/queue/#BTC,1w,weight shows the almost straight line reduction and that 3 s/vB transactions are now being mined.

Does anyone know why the mempool has suddenly started to empty after a long period of being consistently high?