The modern list experience in SharePoint is the default by now. But you can still revert to classic experience by clicking the link under the left navigation. But on communication sites the left nav is turned off by design. If you need to go back to the classic experience you can run this in the browser console:
document.getElementsByClassName("LeftNav-notificationLink")[0].click()Use as a bookmarklet for easy access:
javascript:(function()%7Bdocument.getElementsByClassName(%22LeftNav-notificationLink%22)%5B0%5D.click()%7D)()%3B
My experience is that you need to click the left nav link twice – and thus also run above code snippet twice – to get it to work.
