Editor Not Displaying Properly

Hello everyone!

I was checking a client’s project and accessing the editor when I found that the editor essentially breaks the site. When going into the editor, the format of the site gets all messed up compared to the live site. There is also a pop up message that says “enabled ‘useNewBillingSystem’ beta feature”. Anyone else experience this or know what is going on? I have already cleared my browser cache. I need to send the client editor training, but I would like this issue to be resolved beforehand. I have attached two images, one of the live site how it is supposed to look, and one of the editor where it is broken. HELP!

Correct Live Site:

Broken Editor Site: