I have recently become aware that the PortableApps version of Telegram Desktop is not able to start the webcam stream. The device appears as selectable on the app, but the stream never starts. I have tried downloading the latest version of the installable version and it works correctly there. A quick check showed that the installable version has the path "Telegram Desktop\modules\x64\d3d\d3dcompiler_47.dll", while the PortableApps version uses "Telegram\modules\x86\d3d\d3dcompiler_47.dll".
I can produce logs to better debug what the problem is but I would rather not upload the full logs. If somebody can point me what exactly I should check I can paste those lines.
OS Name Microsoft Windows 10 Enterprise N
Version 10.0.19045 Build 19045