As a fallback, Webflow has now integrated native lazyloading via the loading="lazy" attribute, as far as my quick check showed. I assume for Safari / iOS devices, the expectation is the feature will land in iOS 14 update in two months. I don’t suspect Webflow is integrating any external lazyloading libraries like lazysizes.
I think I’ll keep using lazysizes for now: support for horizontal lazyloading of deep sliders, automatically lazyloading display:hidden images (tabs, desktop vs mobile hover backgrounds), and the sheer consistency of it.
