That doesn't seem correct. Next _does_ still use Webpack - it's what does the actual bundling:
> Underlying webpack improvements: We've made numerous improvements to webpack, including optimizing Fast Refresh and making on-demand entries more reliable.
> After making webpack 5 the default in Next.js 11, we've now officially removed webpack 4. We've worked closely with the community to ensure a smooth transition to webpack 5.
SWC is the equivalent of Babel for transpiling JS, not Webpack for bundling.
> Underlying webpack improvements: We've made numerous improvements to webpack, including optimizing Fast Refresh and making on-demand entries more reliable.
> After making webpack 5 the default in Next.js 11, we've now officially removed webpack 4. We've worked closely with the community to ensure a smooth transition to webpack 5.
SWC is the equivalent of Babel for transpiling JS, not Webpack for bundling.