I've done two clean installs so far and extra two Amd cleanup utility uninstalls and reinstalls with the latest apr29 Adrenalin software none of them simply eradicated the problem.
That flicker bars are more common in low brightness settings and more common on battery. I couldn't capture a flicker eq. while on dgpu and playing games. I've also disabled freesync and varibright but i can see that problem some time to time.
Laptop: Asus Zephyrus G14 R9 4900HS /w RTX 2060 MQ
https://drive.google.com/open?id=1Wow0Gx9-dBEIEf-MLBALtCZUn-C_aCzk video proof.