Find where the start up page is set in Firefox

Recently I encountered a weird behavior where a strange webpage showing up every time when I launched my Firefox. The first thought came into my mind is that my homepage of Firefox had been tampered. It might be changed because some software changed my browser settings to promote something. So the next immediate thing I went to check was to see my Firefox browser settings. To my surprise, the homepage setting was not touched. It would still open the Momentum screen which would display some beaut...

   WINDOWS,FIREFOX,HOMEPAGE,STARTUP PAGE,HAO123     2021-10-02 02:28:53