Originally Posted by Ihave1cat

Just want to update a few things. I think the Bluetooth "polling" is the issue - I'll discuss why I think this is the case in a bit.
I have tried to live with the Digital Key for a few weeks - but it is now not something I could rely on. Let me explain.

I ran into the battery drain issue and was unable to get consistent results. Playing with the Background App Refresh, Location etc had mixed results. Sometimes battery drain was less, and sometimes it was more - but the fact that the battery did not last me as long as it did prior to the digital key being set up.

So, this brings me to my next point. I started trying to "live with it", as taking the phone to the gym was far more convenient than bringing my keys. Sometime between then and now, I started taking the keys with me (and I don't have a reason why) - but, what I did notice is that my battery life was normal, I was like "That's great!", something that I changed (background app refresh, location), or just swiping the app away fixed it, however, this was not the case.
The battery went back to normal because the digital key no longer worked. Like @LiBeRtAs mentioned - no Bluetooth connection. Looking at my phone, the Bluetooth connection is usually registered as being connected to "LEXUS NX" - this allowed the digital key to work.
Now, since the Digital Key no longer works, due to Bluetooth not connecting, made battery life go back to the way it used to be - this seems to point out that the Bluetooth connection was chewing through the battery of the phone. My guess is it was constantly trying to connect to see if a Bluetooth connection to the car was available.

So, that's one thing (presumably) solved. The battery drain was a result of the Lexus App trying to connect to Bluetooth. Of course I could be completely wrong about this, but it's just somewhat odd that everything is fine now.

The bigger issue is why the app suddenly stopped working? The key is still added. As Lexus pointed out - this is a bug in IOS 15.x, but why was it working before?

Let this be a cautionary tale - the Digital Key is not a replacement for a physical key. Although I was able to use the digital key as my main key for a number of rides (as in no physical key with me at all), there is a quite good chance that this could have happened during a real trip, where the digital key stopped working - thus I would be SOL.

For those wondering, no - even if you unlock the car using the app, you can't start it, as the phone and car won't pair with Bluetooth to start the car. Yes - Bluetooth works as a means of communication for audio and calls - but not for the Smart Key.

I'll try a remove-add, but the fact remains that it's not a technology I can trust at this time.