Yes. I’ve tried numerous permutations of the Youtube preset (interpolation, quality, GOP frames, bit rate) as well as various permutations of the settings suggested from this post on Reddit: https://www.reddit.com/r/shotcut/comments/4hxsi3/encoding_help/
Every option when uploaded to YouTube exhibits similar artifacts (some worse than others). As I’ve said, the encoded files exported from Shotcut play just fine with vlc, so it’s YouTube re-encoding and munging the video. Maybe there is some magic setting that “just works”.
My gripe is not with Shotcut - it is a fantastic program.