Descript is not yet officially supported for MacOS Big Sur. There's a bug in Big Sur that's affecting many apps like Descript that use the Electron framework, such as VSCode.
We're hard at work and hope to have a fix very soon. If you need to use Descript, we do not recommend upgrading to Big Sur at this time.
If you've already installed Big Sur, there's is a workaround, but it involves “unsigning” the Descript application, which means you are removing security protections and opening yourself up to risk, such as other malicious software on your computer updating Descript without your knowledge.
So while we don’t recommend you employ the following workaround, as long as you understand and accept the risks, open Terminal, and paste in this command:
sudo codesign --remove-signature /Applications/Descript.app/Contents/Frameworks/Descript\ Helper\ \(Renderer\).app
Note that you will need to rerun this every time you update to a new version of Descript.