I was not successful in getting a web application rendered with its mobile friendly interface by using the User-Agent Switcher & Manager extension. After further digging, I noted that although the browser identifies itself as a mobile device through the user-agent string, the sec-ua-* headers still persist and leak the correct platform to the server:

sec-ch-ua: " Not;A Brand";v="99", "Google Chrome";v="97", "Chromium";v="97"
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: "Windows"

Based on this, I am assuming the application is returning the desktop version of the application to the user.

Is there any method to suppress the browser sending these headers in its requests (other than getting an old browser)? Launching Chrome with the --disable-features=UserAgentClientHint did disable these headers.