Update: I stopped the pop-ups from appearing when I disabled playtime tracking. In the EA app > Settings > My Playtime, scroll down to Playtime Controls and click Manage. Scroll down to Playtime Tracking and click Disable.
I also tested by leaving it enabled and set to the lowest time (30 mins), and sure enough I got the warning at 30 minutes instead of 10 hours. Setting it to 12 hours or Unlimited, it still pops up after 10 hours. Anyway, it's obviously a bug with the app's Playtime Tracker rather than some limitation related to EA Play.
