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 nostr:npub1az9xj85cmxv8e9j9y80lvqp97crsqdu2fpu3srwthd99qfu9qsgstam8y8 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.