Does Canva Automatically Save Progress?
Canva was designed to be dummy proof. Everything about the user experience was made to be accessible for any type of user. This means they automate as much as possible and it also means they don't offer features many design have have - like gradients for example.
There's no gradient tool (as of now), just some premade gradiented layers, but it's just really limited.
Does Canva Automatically Save Progress?
So, yes, as I said - they want to make their app as accessible as possible. This also means Auto Saving - because knowing the average user, they will end up losing their progress constantly.
Another reason Canva auto saves progress is because they are a web app and the application constantly communicates with their server. If you lose your internet connection and your design is not autosaved, you might end up losing all the work.
So to fix this, they simply decided to auto save every time you make a design iteration to your project.
All the apps they have: desktop, mobile and web, all auto save progress. So you don't have to worry about it.