Application Insights security and spoofing

Question

This may be a silly question but is client side application insights safe from spoofing? Microsoft ask you to add a bit of JavaScript to your HTML page that needs recording and

Answer 1

While not exactly a duplicate, i believe the answer is pretty much the same as this one:

How does Google Analytics prevent traffic spoofing

AI doesn't know how or where you're using your key, so how would they know which traffic is legitimate and which is not?