S8+ video playback when streaming is pixelated

[APH50]

Hi can anyone help. When I play video on YouTube (or og youtube) the playback on the phones screen often becomes pixelated, ususlly with a vertical line in it. Strangely if i cast from youtube to my tv there is no issue. I have uninstalled and updated youtube but it hasnt helped. Any ideas? (Screenshot attached)

 

[Rukbat]

If it doesn't happen on the TV, it's not YouTube. Try turning the phone into landscape mode and see if it still happens.

 

[APH50]

Yes happens in both landscape and normal modes. I have also tried adjusting video settings which doesn't seem to make any difference