This seems to be pretty common with E Ink displays unfortunately (you hear the same about many commercial ebook readers). At least the larger ones are more or less all from the same manufacturer (E Ink). I don't know if there is binning going on and Amazon gets better batches than Waveshare does ...

Direct sunlight can also be a big problem for this display tech, so I'm intentionally hanging it on a wall facing away from the most intense daytime sunlight I get.

Hope it survives at least a couple of years.