The only ones that are not affected by this are videos that are 1080p/1440p (2K)/2160p (4K). If you have max resolutions to these types, you are not affected. Youtube wants people to eventually explore higher qualities I guess....
Also 4mbps isn't too bad, but it is noticeable. It's one of those qualities where maximizing it on full screen would look terrible but would still look good not full screen.
Youtube is shit and had been getting worse and worse over the past few years. I can't even open a youtube page anymore, I have to use viewpure.com or add &diable_polymer=1 at the end of urls just to make the page load. A space opened up for easy competition against yt a long time ago, I dont know why nothings filled it.
Also 4mbps isn't too bad, but it is noticeable. It's one of those qualities where maximizing it on full screen would look terrible but would still look good not full screen.