The "patch" was changing to a different frequency band, allowing anyone to block only one system without affecting the other [1]. This is very much different from being able to turn it off.
I think OP meant jam. I believe at some point in the discussions about the Galileo frequencies that the US threatened that they may need to use an ASAT weapon on Galileo spacecraft if they believe the system was being used against them. That would have been the only way to maintain GPS and stop Galileo. So Galileo switched to a different frequency than GPS.
[1] https://en.wikipedia.org/wiki/Galileo_(satellite_navigation)...