Something to keep in mind is that a new season of D3 has recently come out (more interest) while D4 hasn’t had anything in a while (less interest). These two things will be bumping the numbers.
P.S I’m a long time PoE and formerly D3player. I’m stoked I didn’t buy into D4. If anyone hasn’t tried it yet, a D4 YouTuber called Darth Microtransactions described PoE as ‘everything I wanted in D4 but more and free’.