New Outlook App: Refresh apps in Outlook app

We are developing an app for the new outlook with a unified manifest (same app for Teams, Outlook and Microsoft 365). We have a problem in the new outlook app (Web). Our app is correctly shown on startup. When the user tries to refresh OUR app, outlook says the app is not reachable. When the user hits refresh again, OUR app is correctly shown again.

Can somebody explain to us what happens when the user hits refresh? We would have expected that the iframe with our app is simply reloaded, but that is not what happened. What is the new outlook expecting from our app when the user hits refresh?