Replit database.get returns null when used with a parameter but not when used with the value of the paramater?

Question

I have an express GET request I'm using for a login page, and the first step in the login process is making sure that the user exists, but the thing is, while this returns a value -

users.get('Example Username').then((response)=>{console.log(response)})

This does not - users.get(req.query.username).then((response)=>{console.log(response)}))

Even though the fetch request was equivalent to fetch('/checkUser?username="Example Username"')