V1: complains
$$
\frac{x}{y}
$$
V2: doesn't
$$\frac{x}{y}$$
V3: complains
$$\begin{align}
& \frac{x}{y} + \frac{y}{x} \\
& \frac{y}{x} + \frac{x}{y} \\
\end{align}$$
I favor working with V1; V2 isn't a big deal, but V3 is - I write my LaTeX like I write my code, not like an egg salad. Also, it wasn't easy to narrow down to MRE.
Networks that have this format checker are pain to work with. It's not up to users to understand bugs in a detector. Questions (not covered in duplicates from what I skimmed, I checked all):
- Why V2 works but V1 doesn't?
- Why V2 works but V3 doesn't? Is it possible to write vertically-aligned LaTeX, like clean code?
$$<newline><formula><newline>$$produces an error message, and removing those newlines fixes the problem.