Last year, Google planned to retire the classic version of Hangouts for all users. At the time, the search giant said free Hangouts users would be transferred to a free version of Google Chat in the first half of 2021.
9to5Google is now reporting that users on Android and iOS have started seeing a message within the app telling them to switch to Google Chat. Google has slowly phased out various Hangouts features over the past few months, but this prominent message is the biggest step since Google announced its plan to shut down the service last year 
A blue banner appears at the top of the Hangouts app saying “Hangouts is about to be replaced by Google Chat“. It also shows a “Switch to chat in Gmail” button and after you log out, you won't get any new notifications from the Hangouts app. A similar warning also appears when trying to access the web version of Hangouts. When you click the “Open Chat” button, you are taken to the Google Chat standalone web experience.
