The changes to Recents do only matter for those users who prefer the manual syncing of photos and videos to the syncing with iCloud Photos. The manual syncing has always been somewhat restrictive, because the synced photos are stored separately and cannot be deleted directly on the device. They have been treated as second class item all along.
The upgrade to iOS 18 has made the limitations for manually synced items worse - the new Recents albums do no longer double as a camera roll and the synced albums in in "From My Mac" are having new issues and are no longer visible when trying to share photos to some apps.
None of this is an issue, when we are using iCloud Photos for syncing the photos between or devices - then all photos and albums are equal and there are no longer "second class" manually synced photos complicating things. Photos on iOS 18 has clearly been designed to be used with iCloud Photos for syncing. If you do not want to go down this road, you really need to find a replacement app.