Of course it's difficult to be absolutely certain but I think I have been blocked on WhatsApp by a friend I have been close with for over 10 years.
I do understand though because I created a kind of hiatus after leaving a long time between her sending me a message with a question mark and not responding. I was going through a low time and struggling to keep up with messages and spending time with my phone turned off and I just let to much time pass by.
I but the bullet and sent an apologetic and heartfelt message to her saying no pressure but would love to reconnect. Since then I noticed that she no longer has a profile picture showing and the message hasn't moved to a double tick.
I'm sad but at least I now have some clarity and i need to move on and respect that the friendship is likely over.