Avocette:
There is used option "-march=native" which can cause that binaries are not interchangeable on different processors. So if the OS itself run and just compiled KStars does not then delete that string from beginning of script delete all build-* directories so it get rebuild and it should work across RPi4 and 5.

Sergio:
Please run "git tag" in phd2 directory and check if it contain that v2.6.12 line. If not try to run "git fetch --unshallow"

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