That's not actually the case! What you upload is pretty close to exactly the same, unless you choose to watch it under automatic settings & then it might deliver a lower quality version to you, but if you click 4K, you will view it at extremely close to what was uploaded, unlike YouTube that applies some fairly heavy colour, sharpening & noise reduction algorithms to everything uploaded there.
Using this video of yours as an example, it is visible on your video, which is not available in 4K, but rather 1080p as the highest option. Just within the first 15 seconds it is evident on the waves, with lots of random patches going soft in focus, losing the crisp edges to them & is easily noticeable in the sky too with colour differences & the dirty plastic screen effect. There are also some weird roughly 1 second apart pixelated pulses doing something to the upper sections of your video in places!
I think it is a limitation of electronic image stabilisation on the horizontal axis of the Anafi gimbal/camera setup; after some research into the effects of that earlier on today when somebody mentioned this as their thought about it.
