I had exactly the same problem! About 11 hours ago! It seems shopify made a Software change and sth went wrong. The profile picture in my shopify also was not there anymore, and few hours later I saw there is a new menu when clicking on the profile picture.
So 11 hours ago, suddenly all my pictures got replaced by a random picture of my cache. I opened my phone and checked my website, same thing, so I thought I was being hacked. But after checking incognito mode I saw everything was fine. Cleared cache on my computer as well as on my phone solved the issue. As my chrome browser is syncing.