Reappearance of unwanted attachments in Messages strings

[Affects my iPhone 14 Pro, iPad Pro 2, 2015 28” iMac, and 2013 Retina Display 13” MacBook Pro, all running the latest OS for that device]

Basic issue: images and files deleted from Messages strings keep returning from the dead.

Details: My Message app is connected to iCloud on all devices to allow the message strings in all devices stay in sync. My iCloud storage is just 5 GB (I store photos on my desktop Mac, not in iCloud, but do have my Photostream on - it deletes content over time on mobile devices). I have been deleting photos and files from my message strings, to stay within the limit. Deletion on one device in the distant past meant the files disappeared from that string on all devices and computers. Perfect.

Over the past year or so, deleted files and photos reappear. Deleting them from one device doesn’t necessarily remove them from all devices in the first place. Thousands of deleted attachments have reappeared from the dead, zombie-like, eating up the space I thought I had cleared.

Such a simple issue, permanent deletion of unwanted attachment (photos, links, PDFs), made so difficult. From online comments of others, the suggestion is to turn off Message in iCloud, but that would remove syncing across devices, no? ICloud’s memory of that attachment being coupled to a particular string should have been wiped clean, also.

Am I missing something here? Why would iCloud override a clear command to delete? What purpose does that serve? The files in Message are not original sacred versions, so should be possible to be deleted.

My hope is to delete attachments from Messages, have the deletion percolate to all synched devices, and never see the former attachment in that string again. All while keeping my devices in sync.

Any suggestions?