ld-classic is needed for NEWER Xcode in some builds. The new Apple ld breaks compatibility, so Xcode includes ld-classic which supports the old UI. https://www.scivision.dev/xcode-ld_classic/ ffmpeg6 won't build without -ld_classic on my M1. We'll need to check the Xcode version in addition to the platform for this one.
This was on 11.7.10, 12.(whatever's the latest), and 14.(whatever's the latest), with the default Xcode for each system, all installed within the last week. However, all of these systems are Intel.
John