Well that is interesting. I’m viewing these photos on an iPad Pro 2 10.5 with DCI P3 color gamut and they all look very clean with no evidence of which you speak of. I wonder as you what is going on. I have noticed that this forum still degrades full 6000X4000 resolution images which these are. Would you be so kind as to go this link
https://visions4netjournal.com/4k-portfolio/ and click on one or two of the same images and tell me if you see the same artifacts?