"Incoming call popup" is a small windows that shows caller information such as last call, location of caller (city/country level) and operator on top of any windows. If you find it not useful and want to disable it, please follow below steps

  1. Open Blacklist app
  2. Click on 3-dot button, then Settings
  3. Click on "Call" (first row)
  4. Click on "Incoming call popup", then select other position OR "Do not show" to disable.