This is occurring whether pushing to WP Engine or Flywheel hosting. And I get the same issue when switching to a default theme like twenty-twenty-two. I’ve compared the sources between my local site and the staging site - it looks like the core css/js files for navigation aren’t being loaded.
Heres an example of what the menu looks like when pushed to staging.
I’m still facing this issue when I browse the site locally from another pc, e.g. from the development PC it I was using localhost in the URL for the local PC I was using 192.168.1.188 the css styles wasn’t loading.