I don't understand why Google or Brave are cooperating with this, they don't earn anything. And if they're not, what prevents Google blocking Mullvad IPs?
Mullvad is paying to use their API's, like Kagi does. Google is making money on this
Then how does Mullvad earns? This surely costs a lot of money to pay for Google search results.
Leta used to require a VPN subscription. They probably figured the cost weren't that high and the possible increase in future customer by offering it for free would at least cover or even outweight that cost.
Google likely just doesn't care. They know most people won't bother using privacy-oriented services out of inconvenience or apathy.