I’d argue against it… 50% of the time my other half can open my phone if my watch is nearby (even when not wearing a mask). I keep it on for convenience but not ideal for security – if my OH can do it, who else could?
Someone within a distance of up to 30 metres from you (it only works if it can contact your Apple Watch over Bluetooth) theoretically.
In real world conditions, it’s likely to be far less than that and also fairly unlikely. Your Apple Watch warns you when it has unlocked the phone precisely because it wants to alert you if it wasn’t you. You can then quickly re-lock it from the Watch.
The real-world risk is fairly low, in my opinion.
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Interesting. They’re meant to check range very well. In my testing, mine only unlocks if it’s within around 50cm of my watch. Further than that I get prompted to bring my watch closer.
The watch also get a very prominent haptic and sound and a button to quickly lock it. If you do, it temporarily disables Face ID and Apple Watch unlock. Your next unlock has to use your passcode to reactivate it.
They could obviously make it a bit smarter too. Like not unlocking if it doesn’t see a face at all. And not unlocking if the face it sees isn’t your own. But I suspect it was a somewhat rushed out solution.
On the Mac, beyond logging in, it works the opposite way when the system needs your password or fingerprint. You get a prominent haptic on the watch and a prompt to press the side button to bypass that stuff on the mac.
They could bring that functionality to iPhone. So you can either enter your passcode to open monzo, or click the side button on the watch.
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Interesting. They are probably using some Bluetooth signal-strength data modelling to decide whether or not you are “close enough”, similar to the Exposure Notifications API.
When my Apple Watch Series 7 finally arrives (early November) I’ll be able to test for myself!
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Yep, I suspect it’s similar to the proximity stuff with mac unlock, which requires line of sight (nothing between the watch and mac obstructing it or other interference) and caps out at just over 1meter before you get told the watch isn’t close enough.
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Yeah, it’s probably got quite complicated risk-analysis algorithms governing how it works.
I’m sure Apple have extensively tested it too, iOS 14.5 alone was in beta for weeks and they would have been internally testing it for far longer.
Realistically, I’m sure it’s safe.
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This isn’t my experience. I’ve had the odd occasion when I’ve been downstairs watching TV and my watch has suddenly made the unlocking sound, saying it has unlocked my Mac. If I go upstairs, the Mac is unlocked.
How strange!
It must be (incorrectly) calculating that you are close by as line-of-sight through the floor.
It would be great, but I guess the issue is that with the Mac, both of your hands are free most of the time so you can easily press the button. With your phone in hand, it’s much more difficult
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Yes, “my” chair is almost directly underneath where my Mac is upstairs and it’s a newish build, so the floors will be thin.
It hasn’t done it for about a year, though, so maybe there was a bug involved.
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Must admit, I’ve noticed a very similar thing too, where it does seem to go through floors. If I stand in just the right spot upstairs above Mac mini, and bend down, the mac will unlock! Only got it to happen twice though! But it has happened!
But if I move more than a meter away in the same room as the mac and try to unlock it, it won’t unlock!
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Welcome to your new Smart Home. Don’t forget to try dancing a Samba in your kitchen to turn the bedroom lights off! 
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