Some valid URLs contain the percent symbol but the LaTeX mode (I don't
know its official name) treats it as the beginning of a comment and uses the comment color as a result.
Emacs : GNU Emacs 26.2 (build 1, x86_64-apple-darwin18.2.0, NS appkit-1671.20 Version 10.14.3 (Build 18D109))
of 2019-04-13
Package: 12.1.2
current state:
==============
(setq
AUCTeX-date "2019-02-08"
window-system 'ns
LaTeX-version "2e"
TeX-style-path '("/usr/local/var/auctex"
"/Users/furue/.emacs.d/elpa/auctex-12.1.2/style"
"/Users/furue/.emacs.d/auctex/auto"
"/Users/furue/.emacs.d/auctex/style" "auto" "style")
TeX-auto-save nil
TeX-parse-self nil
TeX-master t
TeX-command-list '(("LatexMk"
"latexmk %(-PDF)%S%(mode) %(file-line-error) %(extraopts) %t"
TeX-run-latexmk nil
(plain-tex-mode latex-mode doctex-mode) :help
"Run LatexMk")
("TeX"
"%(PDF)%(tex) %(file-line-error) %`%(extraopts) %S%(PDFout)%(mode)%' %t"
TeX-run-TeX nil
(plain-tex-mode ams-tex-mode texinfo-mode) :help
"Run plain TeX")
("LaTeX" "%`%l%(mode)%' %T" TeX-run-TeX nil
(latex-mode doctex-mode) :help "Run LaTeX")
("Makeinfo" "makeinfo %(extraopts) %t" TeX-run-compile nil
(texinfo-mode) :help "Run Makeinfo with Info output")
("Makeinfo HTML" "makeinfo %(extraopts) --html %t"
TeX-run-compile nil (texinfo-mode) :help
"Run Makeinfo with HTML output")
("AmSTeX" "amstex %(PDFout) %`%(extraopts) %S%(mode)%' %t"
TeX-run-TeX nil (ams-tex-mode) :help "Run AMSTeX")
("ConTeXt"
"%(cntxcom) --once --texutil %(extraopts) %(execopts)%t"
TeX-run-TeX nil (context-mode) :help "Run ConTeXt once")
("ConTeXt Full" "%(cntxcom) %(extraopts) %(execopts)%t"
TeX-run-TeX nil (context-mode) :help
"Run ConTeXt until completion")
("BibTeX" "bibtex %s" TeX-run-BibTeX nil t :help
"Run BibTeX")
("Biber" "biber %s" TeX-run-Biber nil t :help "Run Biber")
("View" "%V" TeX-run-discard-or-function t t :help
"Run Viewer")
("Print" "%p" TeX-run-command t t :help "Print the file")
("Queue" "%q" TeX-run-background nil t :help
"View the printer queue" :visible TeX-queue-command)
("File" "%(o?)dvips %d -o %f " TeX-run-dvips t t :help
"Generate PostScript file")
("Dvips" "%(o?)dvips %d -o %f " TeX-run-dvips nil t :help
"Convert DVI file to PostScript")
("Dvipdfmx" "dvipdfmx %d" TeX-run-dvipdfmx nil t :help
"Convert DVI file to PDF with dvipdfmx")
("Ps2pdf" "ps2pdf %f" TeX-run-ps2pdf nil t :help
"Convert PostScript file to PDF")
("Glossaries" "makeglossaries %s" TeX-run-command nil t
:help "Run makeglossaries to create glossary file")
("Index" "makeindex %s" TeX-run-index nil t :help
"Run makeindex to create index file")
("upMendex" "upmendex %s" TeX-run-index t t :help
"Run upmendex to create index file")
("Xindy" "texindy %s" TeX-run-command nil t :help
"Run xindy to create index file")
("Check" "lacheck %s" TeX-run-compile nil (latex-mode)
:help "Check LaTeX file for correctness")
("ChkTeX" "chktex -v6 %s" TeX-run-compile nil (latex-mode)
:help "Check LaTeX file for common mistakes")
("Spell" "(TeX-ispell-document \"\")" TeX-run-function nil
t :help "Spell-check the document")
("Clean" "TeX-clean" TeX-run-function nil t :help
"Delete generated intermediate files")
("Clean All" "(TeX-clean t)" TeX-run-function nil t :help
"Delete generated intermediate and output files")
("Other" "" TeX-run-command t t :help
"Run an arbitrary command")
)
)