Amazon Prime Video is able to remove a video from your library after purchase.
We are contacting you regarding a past Prime Video purchase(s). The below content is no longer playable on Prime Video.
In an effort to compensate you for the inconvenience, we have applied a £5.99 Amazon Gift Card to your account. The Gift Card amount is equal to the amount you paid for the Prime Video purchase(s). To apologize for the inconvenience, we've also added an Amazon Gift Certificate of £5 to your account. Your Gift Card balance will be automatically applied to your next eligible order. You can view your balance and usage history in Your Account here:
This is the way it has been working for quite some time with all digital distribution networks.
The shocking thing here is that you get compensation, Apple e.g. has never done that, in the past they did not even send a notification if they deleted something from your library.
Yes, the whole concept is scummy. But Amazon at least tries as best as they can in the context of licenses from third parties...