There is not one shred of hard evidence that Cruz’s mom became a Canadian citizen and renounced her US citizenship. There are speculative items of interest and one or two possible items of circumstantial evidence but that’s it. Basically, until someone shows a renunciation of citizenship or a certificate of Canadian citizenship for Cruz’s mom then all of this is mere conjecture.
The only ‘evidence’ I am aware of is the charge that she was a registered Voter in Canada. I do not know if that is true. I also do not know if it is true that only Canadian citizens can register to vote there. That makes sense to me, but I still do not know.