Can confirm. I own a Poke 5P and the ghosting is really more obvious until you've fiddled with the settings enough - and I do mean fiddle here. Might take a while.
Other than that I'm a real fan: latest update delivered dark mode (black background, white text) and like I said above: no ads, no Amazon-DRM, all formats, cloud storage (if you want to), TTS, annotations that are really comfortable to handle, bluetooth.
You are correct, you can sideload, but as soon as you open them in your Kindle, they get an Amazon-DRM; so you can't read the very same files on another e-reader. And - as soon as you go online with your Kindle - said DRM is checked and all non Amazon books deleted. At least, that was the case 10 years ago: I still own a Paperwhite 1st Gen which is now basically defunct.
I switched to a Poke 5P (Onyx) and was surprised at the tons of features. No ads, no DRM and reads basically all formats. Win.
I downloaded all my Amazon-bought books, so I can still read them on PC, but otherwise I'm done with their product.