Hi there, I hope this is posted to the right place.
Up until iOS 16, users were able to select all of their highlights from any book in the books app, and email the highlights to export them. Here's a GIF showing how it worked before: https://d33v4339jhl8k0.cloudfront.net/docs/assets/5eb8cc86042863474d1a75fd/images/5edec6ef2c7d3a10cba8978d/file-bvR8UDOFTe.gif
This seems to be no longer possible in Books in iOS 16, and it means there is absolutely no way to export your highlights anymore.
This makes the Books app dramatically less useful, and alternatives like Kindle (that do allow highlight export) a lot more appealing.