Black screen glitch when unlocking the device with Android app

REPRODUCIBILITY (% or how often): always
BUILD ID = OS VERSION (Settings > About product): 3.4
HARDWARE (Jolla1, Tablet, XA2,…): XA2
UI LANGUAGE: English
REGRESSION: (compared to previous public release: Yes, No, ?): Yes

DESCRIPTION:

When unlocking the deive, if there is an Android app fullscreen there is a momentary black screen, it lasts for less than 1 second but is noticeable.
I don’t think this happend before upgrading to 3.4

PRECONDITIONS:

STEPS TO REPRODUCE:

  1. Have an Android app open and in the foreground
  2. Put the device to sleep
  3. Wake from sleep
  4. Unlock the device
  5. Observe the black screen for about half a second

EXPECTED RESULT:

Should unlock and immediately show the app, no black screen

ACTUAL RESULT:

Read above

ADDITIONAL INFORMATION:

(Please ALWAYS attach relevant data such as logs, screenshots, etc…)