Research shows that mobile users expect to:
see the logo below the fold on mobile sites
tap the logo at the top of a mobile page to take them to a “Contact Us” page
tap the logo at the top of a mobile page to take them to new products
tap the logo at the top of a mobile page to take them back to the homepage
Explanation:
When mobile users navigate through a site, they want an easy way to get back to the homepage. In the study, participants usually expected tapping the logo at the top of a page to take them back to the homepage, and became frustrated if it didn’t work.
Read more here: https://support.google.com/partners/answer/7336289