[AI-Assisted Answer] This warning indicates that ICC (International Color Consortium) support is disabled, which can lead to incorrect color rendering in applications that rely on color management.

   
The patch does not solve the problem, but it removes warnings:   
0002-Only-warn-once-about-the-missing-ICC-support.patch
_https://sources.debian.org/patches/mupdf/1.25.1%2Bds1-5/0002-Only-warn-once-about-the-missing-ICC-support.patch/

Since pulseaudio users are usually semi-deaf and semi-blind, they may try to ignore such warnings, even though they are "repeated 18 times".

Patching an Existing Debian Package [using quilt]
_https://www.guyrutenberg.com/2017/10/06/patching-an-existing-debian-package/

See also:
How to rebuild audacious-plugins
_https://dev1galaxy.org/viewtopic.php?id=6686

1 ddg didn't provide the link from ggl you posted
2 applying patches is above my level of competence

p.s. for anyone in a similar situation this link could be helpful (haven't tested it though)

https://blog.mathieu-leplatre.info/apply-debian-patches-step-by-step.html

warning: ICC support is not available

Why not google it?

https://www.google.com/search?q=warning:+ICC+support+is+not+available

There is a patch (a sort of workaround):

https://sources.debian.org/patches/mupdf/1.25.1%2Bds1-5/0002-Only-warn-once-about-the-missing-ICC-support.patch/

how to get rid of those 'mupdf' annoying warnings that often times fill the whole screen

warning: ICC support is not available
warning: openjpeg warning: Non conformant codestream TPsot==TNsot.
warning: undefined link destination
warning: ... repeated 18 times...

thank you in advance!

p.s. xfce, daedalus (up to date)