I got this answer from GS support (not much we can do about it):
This is an already known bug (DEF-8098). Normally AC doesn't copy the Embedded Library when Copy/Paste between Archicad instances, but in case of user defined materials, it brings it over to make sure no attributes are missing.
Workaround: Remove the MASTER_... gdl-s from the Embedded Library.
AC 25 SWE Full
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