Just today I discovered that Apple Safari on macOS 10.14.6 (latest security update) destroys fine details in large images. I did not install this latest update until yesterday, so this is why I had not seen it before.
There were some new GPU problems introduced in the latest updates, looks like the richest company in the world once again skipped quality control testing. More Apple Core Rot from the jackasses at Apple.
Even on a Retina display, the problem is obvious, which means it is a MAJOR loss of detail—resolution is at least cut in half, if not more.
It looks like images are being downsampled to a much lower resolution and then drawn to the screen—apparently some jackass at Apple put in some iOS code, which has long mangled images above a certain resolution. I just cannot understand this level of engineering gross stupidity.
The modest good news (better than nothing, but little consolation) is that if the image is saved from Safari and then opened in Photoshop, it is intact and the same quality as published on my site. So clearly it is a drawing issue as the correct image is retained in memory.
I have no idea what to do about it nor do I yet know at what size images are affected or if it is a general bug that could degrade images under other circumstances.
Google Chrome is useless; it cannot display very large images at all (just draws a red screen). Firefox works OK.
Click for actual pixels and toggle to compare.