I have this warning a lot on file: Overfull \hbox (202.24913pt too wide) in paragraph at lines 7--8 Here is an example
\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{positioning,calc,arrows.meta}
\begin{document}
\begin{enumerate}
\item The distributor sends a transaction to the blockchain containing
($\sigma_{agg} ||
PK_{V_{1}},\ldots,PK_{V_{m}}||C^{M_\theta}_{PK_{V_1}},\ldots,
C^{M_\theta}_{PK_{V_m}}|| k_{1},\ldots, k_{m})$ where $m$ is the number
of vehicles that received the update.
\end{enumerate}
\end{document}
standalone
or did you use it only for the MWE?