On MathHub/courses/FAU/SMAI/problems/source/math/quiz/defeq1.en.tex I get
in PDF, but the HTML gives me
both come from using
\symdef{funmap}[args=3,prec=nobrackets]{#1\mathbin{\comp{\colon}}#2\mathbin{\comp{\mapsto}}#3}
This is also probably a rusTeX bug.
On
MathHub/courses/FAU/SMAI/problems/source/math/quiz/defeq1.en.texI getboth come from using
This is also probably a rusTeX bug.