I noticed, that when requesting for textDocument/documentSymbol the resulting sections (SymbolKind.Module = 2) only have a number if they are assigned with a label.

A small example would be a document with

\section{Section}\label{sec:outer} % 1 Section
\subsection{Subsection} % 1.1 Subsection

\section{Section'} % 2 Section'
\subsection{Subsection'}\label{sec:inner} % 2.1 Subsection'

The resulting document symbols would be:

1 Section
Subsection
Section'
2.1 Subsection'

So the numbers are correct. But when a section has no label, it is not assigned any number.

Similarly,

\section{Section}\label{sec:outer} % 1 Section
\subsection{Subsection} % 1.1 Subsection
\section{Section'} % 2 Section'
\subsection{Dummy} % 2.1 Dummy
\subsection*{Subsection'}\label{sec:inner} % Subsection'

would result in

1 Section
Subsection
Section'
Dummy
2.1 Subsection'

even though the last subsection does not have a number (it is assigned the number from the previous section, and when Dummy section is removed the number would be 2).
[This is not bad, since we can not use the label anyway, because there is no number.]

I guess my expectation would be for the document symbol to always include the number that appears in the actual document. So the names that are after the % in the code.

I have not looked at the code yet, so I don't know if this is feasible in the current way the document is parsed. I also noticed a similar thing for equations. Equations in the symbol list will be numbered only if they have a label.