Even if the device does not get locked, the behaviour seems different.

Actual case
1. Open any app (other than browser) in foreground
2. Swipe down and tap on lock icon
3. Double tap or push power button to unlock
4. You are presented with the lock screen to either swipe left or right

Buggy case
1. Open browser in foreground
2. Swipe down and tap lock icon
3. Double tap or push power button to unlock
4. Browser magically opens, skipping the lock screen