ISPs can't just turn off all encryption. They can only denial of service connections to downgrade encryption for services that offer it.

Abstract Method for generating inherently weak p-r seed values for elliptical curve cryptography for the purpose of subterfuge. Prior art: This technique has been employed in the popular NIST elliptical curve random seed values as well as a variety of consumer grade equipment.

Then you check Apple's transparency report for the warrant canary. And if you do, you will find that it is no longer there which suggests what you say is true.