Apparently so. I recall this explanation back from 2021:

https://news.ycombinator.com/item?id=26143779

Supposedly, a core patent for the technology expired a year ago:

https://old.reddit.com/r/eink/comments/1e3icaz/any_company_d...

It's probably too soon to easily tell whether that's enough to make e-ink screens cheaper and more available.

There are patents on nearly every active component in the cheapest of electronic devices. I don't think it's patents.

There are many tens of millions of e-Ink store shelf-edge price labels around, for example, and they're a cheap commodity item.

If only there were some article on the topic of why there are no cheap ereaders... I hope somebody posts one to HN soon.