This won't help many people but it lets me re-create the Camera Roll/Recents/or whatever it was called.
TLDR: If your use-case matches mine (below) then the quickest way to get at the pics that used to be in Camera Roll/Recents/Whatever is to search for "iPhone" in Photos and this will find only photos taken on an iPhone because the camera name goes in the meta-data of the images. I appreciate that this won't help most people here cos my use-case is a bit odd.
My use-case is that I only use the iPhone camera for snapshots/convenience. Say a product label if I want to buy something or an amplifier wiring before I take it apart or a quick scan of a document that I might need or a baking disaster to share with mates in the pub. Just temp stuff that I might or might not need to keep but can't be bothered to delete. These don't get synched to my Mac or to the cloud or anywhere - they reside only on the phone and should I want to keep them then I import them to the Mac, delete them from the iPhone and add them to the set of folders that get synched to the iPhone from my Mac . Then, I have a number of cameras that I use to take photos I want to keep that will go in my database and these synch between Mac and iPhone via Finder and USB. I also have a bunch of scanned photos going back to the 1960s which are also synched between Mac and iPhone via Finder and USB. These pics are all tagged with the camera or scanner model so they don't show up in the "iPhone" search.
I don't think it matters, but note also that I don't use Photos on Mac. I use a semi-pro image management programme that better meets my needs. When I do import pics taken on an iPhone I can easily change the camera from iPhone to something else so that it doesn't appear in the "iPhone" search described above.