This is rather a pain if the colors are branding colors (Corporate logo, etc., or colors that MUST be correct like showing colors of paint, clothes, wallpaper, yarn, etc. that must meet with the end-consumers expectation). They need to be EXACT colors.
Likely, your color managed browser reads each files embedded color profile and converts it to the monitor profile so if the monitor is not adjusted correctly, you get washy-colors, off-colors, etc.
I need to 'adjust/correct' my monitor colors, I'm sure. Every time I do a website review and complain about the colors, the owner of the site expresses surprise as what I am reporting, they do not see... Surely, they fault cannot be entirely theirs alone. I have heard this reported back to me too often for me to not be at least partially to blame..
Have you tried any online-adjustment sites. -I have not, but here is one that might help or give ideas what to adjust:
At least, knowing that YOUR monitor is correct takes the onus off of you for the image colors, if this is not the actual fault..
Note the line: "...Mac computer monitors should calibrate to 2.2 gamma, 6500/D65."