iframes with data uri doesn’t work on capacitor apps:
<iframe src="data:text/html;charset=utf-8,%3C!DOCTYPE%20html%3E%3Chtml%3E%3Chead%3E%3C/head%3E%3Cbody%3E%3Ch1%3EHi%3C/h1%3E%3C/body%3E%3C/html%3E"></iframe>
this works fine on web, but not inside a capacitor app.
I reported an issue for ionic, but maybe it seems more a capacitor related bug.
data uris works fine for images, but not for iframes.
I checked also CSP
example repo