Adaptive brightness is not present in notification bar and altogether does not work
Android has removed &quot;Auto-brightness&quot; in place of &quot;Adaptive brightness&quot; on Android 5.0 Lollipop.
From Android Police,

If you're looking for the auto-brightness switch on the Android L preview build, you won't find it. That's because it's been replaced with the adaptive brightness toggle. [...]
In short, adaptive brightness is like quasi-autobrightness. You're essentially setting a &quot;range&quot; of available brightness levels when this feature is turned on, so that if you have display brightness set to 50%, the phone may only actually adjust itself between 40 and 70% brightness in a given situation. This is as opposed to completely automatic brightness, which typically gives you the full spectrum of brightness adjustments depending on the ambient light. The problem with fully automatic brightness is that's it's often slow and a poor judge of what level of brightness your eyes really need. So, this adaptive mode allows you to set a baseline brightness that the phone will then adjust from based on your surroundings.

If adaptive brightness is active, it will be always active even if the brightness is changed from the quick setting panel, because it will only change the baseline brightness.
On the other hand, it's correct that there is no quick setting to toggle &quot;Adaptive brightness&quot; on stock ROM. It seems the only way to do that is with 3rd-party apps, but I didn't found any as of current writing.