A significant change under the hood for WebDriver is the complete W3C compliance of the WebDriver APIs. This standardization will eliminate the need for encoding and decoding the API requests by the JSON wire protocol in Selenium 3 and earlier versions for communication between browsers and test scripts. This means the WebDriver will now interact directly with the target browser.
This standardization will result in more stable cross browser tests. However, the change in protocol won’t impact existing users as popular browser drivers like ChromeDriver and GeckoDriver have completely adopted W3C protocols. In a nutshell, JSON wire protocol is deprecated in Selenium 4.
