Hello Amin,
Maybe you can get more information about the issue. My point is that I am not sure if the content policy (which apply to the app which run inside the IFrame, and not apply in the "parent") has something to say here, just because what I say: the content policy is for the app itself, not for the "parent".
On the other hand, if I search by "unsafe posfix" I can't get relevant results: maybe I am not searching well, but, it's rare to see no results when we search for an error: commonly we get relevant information which can be used to discover a possible solution for the error in question.
So here are some questions... is the AB1 app loading in the IFrame? If yes, then... I do not understand the problem... since probably this is what we wanted... if not... then we must get some kind of error... probably related with the server which serve the AB1 app and not the app itself.
Are you tried to run the AB1 app inside an IFrame to see what happen? Doing this we can see if the problem is in the server of the app: some servers can refuse to load the content inside an IFrame, even when I am not sure if this is the case, we can look into this to see if that is the problem or not.
Maybe the "unsafe posfix" error is related in some manner with Capacitor and my leak of knowledge about Capacitor don't allow me to say something useful: maybe this can be a clue, I mean, maybe we must search about that error talking specifically about Capacitor, to see if it's a Capacitor problem / error.
So try it with all of these, Amin, and, try to get some more information, or to reproduce the problem, in order to see what can be the possible solution. But again... I am not sure about the security policy, which in principle affect to the app itself, not to the "parent" app...
I hope you can finally solve the issue! And please, don't hesitate to post here any further questions!