It's a common discussion topic -- a few links:

Bad UX: How Booking.com deceives clients

https://news.ycombinator.com/item?id=15152155

https://medium.com/@ilyadoroshin/bad-ux-how-booking-com-dece...

How Booking.com manipulates users (ro-che.info)

https://news.ycombinator.com/item?id=15297915

https://ro-che.info/articles/2017-09-17-booking-com-manipula...

[dupe] Dark Patterns (darkpatterns.org)

https://news.ycombinator.com/item?id=20858714

https://www.darkpatterns.org/

Successful machine learning models: lessons learned at Booking.com

https://news.ycombinator.com/item?id=21182445

https://blog.acolyer.org/2019/10/07/150-successful-machine-l...

Dark Patterns at Scale: Findings from a Crawl of 11K Shopping Websites (2019)

https://news.ycombinator.com/item?id=25968531

https://webtransparency.cs.princeton.edu/dark-patterns/