Hmm there is an issue about this
However I did implement this feature, I didn't release it yet though for some reason.
This doesn't need a flag to enable it - maybe it should as it potentially has to do more work (a HEAD request on each object before copying it).
Can you try this
v1.54.0-beta.4773.1528c78d0.fix-111-metadata on branch fix-111-metadata (uploaded in 15-30 mins)