If the screenshot in
this post is what you mean by in-book stats, then ePubs have never had them, they are only displayed in KePubs.
In the current firmware, and I think since version 3.13.1(?) those stats are shown for sideloaded KePubs too, but there were some older firmware versions where they only worked for KePubs synced from Kobo.
But beware that while the stats are shown, they may not work correctly if the book's TOC has missing entries. The books synced from Kobo will (or should) have any missing TOC entries filled in, but KePubs created by Calibre might not.