Scope is blacked out, doesnt happen everytime when it happens it cant be fixed by changing weapons only by dying.
Unfortunately it's not just the Panzerfaust 3. It's any scoped guns. Like you said the only way to get rid of it, is either resupply or respawn.
Blacked out scope was already a bug. They didn't fix it and others for update. Hands and bodies invisible bug still happens too.