@machadoug - I have given up on using the Auth Token based app extension, as I had too many problems to get it working.
Instead, I changed my code to use JWT with Passport and local Mongoose strategy for authentication. The latter (local Mongoose strategy) is of course only relevant for you, if you use Mongoose at your backend.
@midas If qgrid is a quasar app extension, then they have not adjusted their app.compatibleWith in app-ext/src/index.js
It should look like this to get rid of the issue: