Over two years after Microsoft discontinued support for Internet Explorer 10, Google has announced they will stop supporting the legacy browser on Google+ starting October 23, 2018. It means that Google will no longer do backwards compatibility testing for IE 10 and rendering issues or access to certain features could be limited after that date.
Technically Google across all of G Suite only supports the latest version of Internet Explorer, v11, as well as Microsoft Edge from the Redmond, Washington company. This is more-or-less just solidifying that stance in relation to G+.
Microsoft themselves quit supporting Internet Explorer 10 back on January 12, 2016 so Google’s decision isn’t out of line by a long shot. Users of IE 10 are encouraged to check out the supported browser page at Google to see what versions of Internet Explorer, Firefox, Safari, and Chrome are supported by the various G Suite sites and apps.
Like so many different apps used today, it is always a wise choice to use the latest and greatest, particularly when it comes to browsers. Given their role of being our gateway to the Internet, they are the most vulnerable to security breaches and attack. Using a more contemporary browser is just good security.