Our old phash fuctionality relied on an older Linux library named pHash which hasn't been supported or updated for numerous years.
pHashing (use DCT) is a pretty standard functionality now, and we have written our own pHash functionality (we are happy to share it with you if you'd like).
There are no current users of the legacy one, so we are sunsetting that one and relying on our new one going forward. The new one is NOT compatible with the older pHash libraries. The biggest users of pHash is ourselves as it's part of all our internal testing to make sure the outputs of files stay the same when changing libraries.