So, the only official response from Apple, which was a pedantic suggestion/explanation of how to copy/paste from NOVEMBER 29th, there has been no other explanations why problems persists.
Was this change by Apple intentional? If so, why? The work-around to this silliness is you have to save any image you want to copy, instead of copying it, then select it from where you saved it, copy it, and THEN you copy it and paste it into messages.
If I was a conspiracy nut, I'd say they want you to save a bunch of images you don't want to keep, forget about them, and then have to pay for more iCloud storage.
Sounds ridiculous...if only we could get a real response to why this is how it is with Big Sur. We're WAITING.