Recent versions of Xcode, most likely starting with Xcode 15, do not produce deterministic binaries/libraries out of the box. In particular, the UUID data in the LC_UUID load command is not stable.

After spending some significant time trying to understand why, it turns out that the linker has started including the last modified time stamp of the object files in the (debug?) data and that time stamp data is included in the computed UUID "hash". So even if the rest of the data is the same between two builds, the build time (or, more accurately, the time when the object file gets written to the file system) now affects the UUID and therefore the data of the resulting .dylib files.

It seems (unconfirmed) like this may be an artifact of Xcode 15 using a new linker ("ld-prime") which may or may not be why the behavior has changed.