webm problem in Shotcut, FFMPEG, Openshot and a workaround

Problem: If you record your screen in Windows or Mac using Nimbus screenshot which saves the recordings as webm format then try to process the recorded webm files in Shotcut, FFMPEG or Openshot, it works terribly. The core problem appears to be from ffmpeg, which is used by Shotcut and Openshot that is unable to decode / encode webm files created in windows correctly.

Even if you try to use FFMPEG to convert the webm videos to mp4, the audio quality reduces drastically.

Workaround: I used Movavi video editor to edit these webm files and it worked great !