[bscphil]

Are you using the beta? If not, that's expected unless you have the mode=1 setting I mentioned in my top level comment. I have that set on Linux and everything works as expected. (I haven't tested this on macOS at all so it's possible the setting isn't even functional in Firefox 88 for Mac.)

[tim--]

I am using the Beta. Testing with both mode=1 and mode=2 causes a no purple tick to show on macOS.

[bscphil]

Oh that? That's a different thing. You need gfx.color_management.enablev4 for ICCv4 profile support.