That is such a bold claim that is obviously not true.
These customers include:
Bosch : https://www.mongodb.com/customers/bosch
HSBC : https://diginomica.com/hsbc-moves-65-relational-databases-on...
SEGA Hardlight : https://www.mongodb.com/blog/post/sega-hardlight-migrates-to...
HMRC : https://www.mongodb.com/blog/post/mongodb-microservices-help...
DWP : https://www.mongodb.com/customers/department-for-work-and-pe...
Liberty Mutual : https://www.mongodb.com/blog/post/liberty-mutual-iac-mongodb...
MetLife : https://gigaom.com/2013/05/07/with-300m-earmarked-for-tech-i...
There is a more complete list here : https://www.mongodb.com/who-uses-mongodb
That list is limited is just the customers that are willing to be public references.
Every mature NoSQL vendor has a similar list.
Google has Firestore as one of their approved databases for internal use.
Those are ones I have first hand experience with.
I know from friends that Microsoft runs things on Cosmos.
Netflix is pretty invested in Cassandra.