CMAKE_OSX_DEPLOYMENT_TARGET not working as expected

My top level CMake file says:

set(CMAKE_OSX_DEPLOYMENT_TARGET 13.0 CACHE STRING "Minimum operating system version for deployment")

and I am building on an ARM system running Sequoia (15.4.1) with XCode 16.3 with the target set for X86_64. The file command confirms:

amonra@Saturn MacOS % file DeepSkyStacker
DeepSkyStacker: Mach-O 64-bit executable x86_64

If then take the signed app folder over to a Ventura system (13.7.5) it tells me:

You can’t use this version of application"DeepSkyStacker" with this version of macOS

Doesn’t make sense to me - what’s going wrong?

I added FORCE to the end and that solved the problem.

David