Is there a way to identify the Gimp version that produced a file (actual Gimp version, not XCF format version)? Out of curiosity, I’d like to know if a file I have comes from 2.2 or 2.4 (timestamped in later 2007, so very shortly after 2.4 was available).
I don’t think there is, unless there are side-effects of some features from these versions. In any case, the XCF format does not store the version of GIMP, only the one of the XCF format. Such info would typically be in the header: GIMP Developer - Documentation of the XCF file format