I use CMake and Xcode 15.0. The manifest creation fails because the plugin is not yet codesigned (Xcode signs the plugin after the CMake Post Build Rules).
So, if I want to solve this issue, I should set VST3_AUTO_MANIFEST to FALSE, then add a script to codesign the plugin in the CMake Post Build Rules, and then add the script that generates the manifest using juce_enable_vst3_manifest_step(). Is that it?
By the way, XCode will re-sign the plugin again after the CMake Post Build Rules.