We use 2 static library in our project. Once the libs were added via "Build Phases > Link Binary with Libraries", they are shown in the "General > Frameworks, Libraries and Embedded Content".
Unlike other frameworks, there is NO "Do Not Embed" option for these 2 static libs.
So my guess is they are embedded into the final binary without code signing?
And the problem is only found on the iOS 14.5+ devices.