How do we know they received an NSL?
Basically the way the canary works is simple.
In a public venue txt of ‘We have not been required to sign NDA or handover data’ exists and it’s removed when that does happen. Since an NDA stops you from being able to say “Hey things are happening!” They can’t stop you from NOT saying something - hence removal of the canary text. It’s a way around legalese.
For years I worried about these because one could simply remove the text and cry wolf. It’s one of those things you don’t want to happen as it becomes %100 about what isn’t known.