What Microsoft says:
Microsoft Silverlight will reach the end of support on October 12, 2021. Silverlight development framework is currently only supported on Internet Explorer 10 and Internet Explorer 11, with support for Internet Explorer 10 ending on January 31, 2020. There is no longer support for Chrome, Firefox, or any browser using the Mac operating system.

What Wikipedia says:
Microsoft Silverlight (or simply Silverlight) is a deprecated application framework for writing and running rich Internet applications, similar to Adobe Flash.

So, if you have Silverlight installed on your Mac, you might as well delete it now.

John R Carter Sr