Microsoft blocks Firefox in new Skype for Web

[Puppy2012]

Those who still use Windows 7 or 8.1 on an old machine and don't want to use the terrible slow and non-native Skype 8 application have option to use Skype for Web https://web.skype.com/ in a web browser for simple text chat (I don't need anything else).

Now there is announcement "Support for this version of Skype for Web is coming to an end. A new preview version is available now for Microsoft Edge and Google Chrome with HD video calling, call recording and much more." No, I'll never use anything Google based.

Is there any technical reason behind or Microsoft is playing bad again? I tried to spoof the user-agent by an addon and the new Skype web site https://go.skype.com/skype.preview.web works ok.

[Puppy2012]

Also users on other platforms are affected.