I was having 50-60 reviews a day last week which suddenly dropped to 15-20 a day. I am compensating by catching up on lessons but I know that in the past it meant more apprentice backlog which lead by sudden increase in reviews. But the projected number of reviews remain low. Is this a new feature that comes with new content being added?
Edit:
Mistery is solved. It is “Tsurukame” app sync issue. The app was showing 11 reviews but there are 144 on the web page.
I reported a bug but was advised to keep an eye on “pink bar” that should be indicating that sync happens when you open the app.
I am now slowly dealing with the damage by speeding to close all accumulating reviews to catch up.

