I received a user's feedback, he got an error in https://www.mediawiki.org/wiki/Extension:Math/Inputtypes

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "/mathoid/local/v1/":): {\displaystyle d/dxf(x)=lim_{h->0}(f(x+h)-f(x))/h}