Single item array query parameter not correctly parsed in Azure App Services in 5.2.1

[jur-clerkx]

When we deploy our app on Azure App Services, a single query parameter is not parsed when using the ?param[]=value notation. Express will show this as a query param with the name param[] and the value value, while locally we get the correct behaviour: param and value [value]

Environment information

Version: 5.2.1

Platform: Linux Azure App Services

Node.js version: 24

Any other relevant information: Issue only occurs when running on Azure App Services. When running locally, it works as expected

This issue started for us after upgrading to the 5.2.1 version. We had no issues when running the 4.18.x version

What steps will reproduce the bug?

Add a debug endpoint, e.g.;

router.get("/debug/query", (req: Request, res: Response) => {
	const rawQueryString = req.originalUrl.split("?")[1] ?? "";

	return res.json({
		parsedQuery: req.query,
		rawQuery: {
			queryString: rawQueryString,
		},
	});
});

Send a request with the query format ?param[]=value.