Purchased a book (2019) in the iTunes store - now it can't be moved to a new ipad - why?

I purchased the book C++ Concurrency in Action in 2019 on my phone. I have since tried to move that to my recently purchased ipad. But it fails because the store claims that the content is no longer available in my region. It was originally available at this url.

https://itunes.apple.com/WebObjects/MZStore.woa/wa/viewBook?id=1454683083

But it's not listed with that ID anymore. It's now here.

https://books.apple.com/us/book/c-concurrency-in-action/id1572387608

I think the store sees these as two different products which is why my purchase is likely forever orphaned on my phone. And yes, I did purchase my book in the same region I'm in now.