Dear Jimmy,
New answer from Steffen and then he closed the issue:
Thank you.
From my understanding, disallow_webview=true was at the time just way for developers to test whether their apps would be impacted by Google blocking embedded webviews in their OAuth 2.0 authorization flows before making the block effective for everyone.
You can add a query parameter to your authorization request URI to test for potential impact to your application before September 30, 2021
If the question is about how to add that query parameter anyway then I think you need to dive into Google's documentation and get a better understanding of their OAuth 2.0 authorization flow. I do however not think that this applies anymore.
To me it seems like this is on Google for dictating what type of browser is permitted in their authorization flow, and I think that every solution is going to be a workaround.
Should you find that there is a specific technical limitation in this webview library or how it integrates with the underlying browser engines (not only MS WebView2) then I suggest making a new, more specific issue with those details.
I will close this issue as I do not see any way to move forward
If you could explain, step by step, how to reproduce it here maybe we can think about a solution. Please post an animated gif or several screenshots.
many thanks