About:blank in capacitor app instead of.. my app

Sometimes when I open my Capacitor App on my iPhone, I get shown a totally blank screen instead of my app (blank webview)

Safari web inspector calls that page about:blank and the page has this HTML content:

<html><head></head><body></body></html>

If I remove the app from app switcher and open it again, then it works.

What’s causing this and how can I stop it from ever happening?