With 4.15 kernel, the display was working correctly, but my sound card Realtek audio wasn't working. That's why I changed kernel version to 4.19 (this is the first version which works with it) but the display went wrong.
I've tried Why is Display flickering in Chrome/Chromium of Zenbook UX303UA with Google Plus? and After most recent kernel update (4.15.0-44-generic) my tablet freezes whenever plugged into docking station to fix it but it didn't work either.
I've tried 5.0 kernel too, but it is just worst.