The spacing after an operatorname seems too tight in certain situations (compared to v3 and "real" LaTeX anyway).

E.g.,

<p> Pulling back the Jacobson topology on $\operatorname {Prim}{\mathfrak{T}}$, we obtain a topology on $\operatorname {Spec}{\mathfrak{T}}$ 
</p>
<p>Let $i, j \in \mathbb{I}$ such that $4\lt \operatorname {ord}q_{ii} + \operatorname {ord}q_{jj}$. </p>

This could lead to confusion if font style is the same, e.g., imagine something like $\operatorname{ord}\mathrm{er}$

MathJax v4-beta.3 rendering

"real" LaTeX