XnView Software

my default 'pixel ratio' is "D1/DV PAL (1.07)"
after I changed it to "square", wow, the issue is gone!

I tested the different zoom quality options:
bilinear, bicubic, spline16, spline36, lanczos3, lanczos4

bilinear: incorrect image at initial 100% viewing
the remaining 5 methods: initial 100% viewing ok -> incorrect after zoom in->zoom out /or/ after zoom out->zoom in

I tested the picture (med1) on different PCs.

incorrect: MSI (Intel i5-6400, NVIDIA GTX960)
incorrect: MSI (Intel i5-8400, NVIDIA GTX1050)
incorrect: MSI (Intel i7-10700, NVIDIA GTX1650S)
ok: ASUS (Intel i7-7500U, NVIDIA 940MX)

Weird enough, it's ok for med2.jpg for all PCs.

The issue remains whether or not an ICC profile was used.
Another interesting observation is that when I saved the JPG file to either a PNG or TIF format, the issue still existed.

Intel i7-10700, GTX1650S 4GB, 32G RAM
OS: Win10 Home 22H2, XnViewMP 1.4.3 64bit

When I zoom in/out the same picture, for an unknown reason the color changes.