For me, I've mostly switched to reading on my phone. Dark mode, plus OLED, works very well for my needs.
But the Overdrive issues are infuriating, especially when you miss out on a hold from the library and have to get in the queue again. On popular books it can take months. :(
FWIW, I've had the same issue with my Kindle, and cleaning the screen seemed to fix it reliably.
I use Koreader: after experimenting with various configuration parameters for a few days, the UI is now stable and tailored to my taste. Once in a while, I switch to another app: Plato is better at handling huge PDF files.
Another bonus point is that I can mount my ereader as a USB mass-storage and rsync the git repository of my ebooks onto it.
So you could even just git push.