Microsoft decided to concentrate on the Edge, and Google Chrome.
March 7, Microsoft has updated the browser version of Skype. After that the messenger has stopped working in many browsers, in particular Safari, Mozilla Firefox, or Opera.
At the same time, browser based version of Skype available for users of Microsoft Edge, and Google Chrome and Chromium browsers, like Vivaldi.
Why this happened. As explained in Microsoft, function calls and multimedia version of Skype in real time different is implemented in all browsers. Therefore, Microsoft decided to focus on Edge and Google Chrome.
That Skype will not be available for users of Firefox, Safari and Opera, the company announced in January.