UI of the application changed afyer generating report from lighthouse

I have made an MERN application. Then I tested that application using lighthouse from chrome. After generating report, my application's UI got changed. I don't know why it's not showing my UI as before even after reloading page, restarting server and also restart the laptop. The login page had 3 input bar and were at right side and a photo at left. After generating the report, the UI changed to all elements stretched out. Each element's width is as big as viewport width.

This happened in branch_eg1. In master branch it wasn't like that. It was all good as before. But when I pulled the code and merged with master branch, then same behaviour happened with master branch.

Please help me to look out of this.