Tried to mod latest Youtube APK named 5.17.6 Google have made it all impossible to change something all methodnames and classnames are random alphabetical marks and file directory itself is a real mess, no potential by finding somethid through folders, ad removal also hardened through a method, after hours of searching I finally found line which was getting phone's capability to stream higher resolutions than 720p or not, but after a change of it's code verify error popped up because of other method checking the value change, thanks Google...
But for older Apps with normal structure I could enable screenoff, up to 4k streaming and adless.