Regression in epochs metadata generation via change introduced in #12347

[hoechenberger]

Originally posted by @hoechenberger in #12931 (comment)

@larsoner @cbrnr I think it's caused by this change from #12347

https://github.com/mne-tools/mne-python/pull/12347/files#diff-a6032a51226f9175d84fb340bab2a4238ddc24bf0c0f979bd1921f9d2f54c9fbR2993