I am a many years Booking.Com user, but since about 4 years I stick to this pattern: look up hotel on Booking, then go to hotel's website, register account there and get a member rate or privilege. In exchange they will at worst send me some email marketing once, which is easy to unsubscribe.

In larger networks I also getting some bonus points, but the main benefit of being a direct and even registered customer is an attitude of hotel. Most of the time it is better room or even upgrade, or just an available ear for requests or complains.

The reason of that is a visible disloyalty and even dishonesty of Booking.Com site and app towards me. I am just not in the mood to de bullied and dark patterned by a search engine.