In which scenario "webApplicationInfo" nad "validDomains" needs to be configured in manifest.json?

Thank you very much for the quick confirmation!

Regarding 2nd question, let me confirm 1 point.
I could understood "QnA Maker endpoint" need not to be configured in "validDomains" as there's no UI rendering.

But regarding "token.botframework.com", as per the below official doc, it's mentioned that it needs to be set in "validDomains", but in my case, app works without this configuration and also from your explanation, seems not necessary.
Is it really necessary in this scenario then?

https://docs.microsoft.com/en-us/microsoftteams/platform/bots/how-to/authentication/add-authentication?tabs=dotnet%2Cdotnet-sample#install-and-test-the-bot-in-teams

Thank you very much!