All E-ink does that flash. I have a thread here from when I first started messing around with a Nook. Ive seen many other E-ink readers, same thing. Kindle, Ive seen people use it, same thing. It annoys me as well, I really hope one gets used to it after awhile. Itd be even better if they release an update or even a newer version that doesnt have it at all.
https://www.mobileread.com/forums/sho...d.php?t=105450
Heres the thread.