One concern on mobile where I find the scrolling is not respond for a second or longer whenever I swipe back to previous page in Safari, applicable in some of the showcases in Next.js too, is it the expected user experience?
People are calling out the routing issues specific to next.js ... I am not using that, but am using react with redux and routing (connected-react-router) and haven't experienced the types of issue you mention. Though many on here point out that next.js routing is a major shortcoming.