Why do prototypes viewed via mirror or in the cloud show occasional flashes of purple outlines around layers? This doesn't occur in Framer's built-in canvas.
I've also noticed some differences with TextLayers—I have some TextLayers that look fine in the built-in canvas, but that wrap awkwardly when viewed in a browser.
Those are 'hints' for clickable layers. You can turn them off if you want, and the docs will have the info.