Could be such a simple thing as getting rid if an overflow for tax reasons, but I’m not well versed in USA taxes except it’s horrible so don’t take it as fact.

Proton was created to serve the world, and the non-profit Proton Foundation ensures that this can never change. As Proton’s primary shareholder, the foundation exercises its control to ensure that Proton does not deviate from our mission to build a better internet that serves the interests of all of society.

Edit: meaning, there’s a difference between the foundation and the company