It just takes time for the current week numbers to accumulate as people check-in to their accounts and therefore add to the 'active users' metric. 
I think @NVK was guesstimating somewhere in the 100k range which could be the case if you look at npubs that check in every so often and with a different filters to try to account for spam. It's hard to say the real number eg, people in Japan using japanese based relays may not be picked up. 

 Interesting 🧐 

 If you check the daily stats now until 00:00 UTC (approx 1hr 15mins) it will likely look as you had expected @I satoshi with you