1. Google indexes the URL content of the mobile version, but the user will see the desktop version if on a desktop assuming it is different from the mobile version.
  2. Crawl counts are switching to mobile majority opposed to desktop majority.
  3. Google isn’t showing cached pages for several mobile-first sites. It’s a temporary bug they are working on fixing asap.
  4. There is a speed update coming in July that is not related to Mobile-first indexing.
  5. Hamburger-menus and accordions are fine on mobile and won’t negatively affect rankings

Learn everything you need to know about Mobile-First Indexing and how to prepare for it with this guide from Search Engine Journal.