If you use a third-party app to create a slide-out cart, then you will likely want to disable dawn’s (new) built-in cart drawer.

Leaving both will cause an issue where you will have to close two different slide-out carts.

In Dawn 7.0.0+ (currently using 7.0.1) the fix is to remove the cart open event from the renderContents function.

Open assets/cart-notification.js and scroll down to the function renderContents(parsedState).

For me, this was on line 34 but it may be further or earlier depending on any customizations you have made.

Simply comment out this.open() near the bottom of the function and that should be all.

The function declaration responsible.