I am pretty new to Mariott Bonvoy as I am mainly used to Hilton and IHG.
For example, IHG has something known as "Best Price Guarantee". If the price on their website is more expensive than a room on a 3rd party, you get points refunded.

Today I wanted to book at a new hotel in Greece which offers rooms at 270€ per night in May.
When I visited their official website I was able to book the same room for just €200, but including dinner per person per night. There was also a cheaper room available that was not seen on Mariott Bonvoy. I am surprised that if you are a loyal member, you might end up booking a room for much more, that seems ridiculous?

Is there something like "Best Price Guarantee" at Mariott Bonvoy?