Is this even a surprise? Giving away free access to Copilot hemorrhages money and only exists to convert those users into paying customers. It costs them nothing to take away some features from these users.

The only real ways to prevent this are local hosting (which is much more realistic these days) or an explicit contract stating that the features you want will remain for the duration of the contract. The latter is not an option with GH Copilot, as far as I’m aware, and is basically nonexistent with any modern services.