A couple of days ago I noticed this as well, I didn't look at the source but it is possible that the seesaw algorithm has been changed in v2.3.0 and that the payment stats are still based on the older algorithm.

The number of MN decreased considerably from ~2200 to ~1550, that might explain the lower reward for staking, I guess a number of people switched from MN to staking because that was more profitable the last 5 weeks.