function setFaviconUrl() doesn't add favicon - why?

Question

this code is not working, and I don't know why. I have tried to change picture, tried .ico file and it didn't helped. There is even no error in Chrome console.

It worked for some time, but it stopped woking "randomly" without any obvious reason. Google's documentation

   function doGet(request)
    {
      return HtmlService.createHtmlOutput("Ahoj").setFaviconUrl('https://humandesign.cz/scripts/frontend/favicon.png').setTitle('FrontEnd');
    }

Answer 1

Apparently this is a known issue and Google is working on a fix: https://issuetracker.google.com/issues/119627744