That's my update to it, couldn't reply on the original post due to an error message so I opened a new one
Unfortunately I didn't get any answers or help from the slingmedia team to my issue, in the meanwhile I've noticed something more, those stripes are especially present on fullHD setting! but otherwise it looks completely clear on 1920/540 !?
And it's only on the slingplayer for desktop on windows 7 but not on webplayer or slingplayer App (IOS)