Vagaries of HDMI maybe? They do some really weird things at the top end of the bandwidth. I've got a contract HDMI cable that we used to buy by the pallet load from China in the early days of HD - this is back in the early 2000's, way way before 4K, HDR and all the confusing stuff - It's 15M long (50ft) and I installed it in 2005 when we built an extension and I convinced the wife a cinema was a good idea. It will take a full 600MHz signal no bother, but then it is the thickness of your little finger - actually, probably ring finger. Trying to find a 50ft cable that does that these days is like flying to the moon.