Copy/Paste image from Photos to Messages converts HEIC to JPEG and loses resolution on macOS

I want to send images from macOS Photos in an iMessage conversation. When I **copy/paste** an image from macOS Photos to iMessage, it is converted to a JPEG file and downsampled. This loses the Live Photo video and results in a much lower resolution image. --- Original image from iCloud Photos Library on macOS: > .HEIC, Live Photo, 4032x3024, 1.1 MB --- After copy/paste to Messages and send: > .jpeg, not Live Photo, 1024x769, 218 KB, creation and modification dates have been changed to today. --- If I instead **drag** the photo to the Message conversation, rather than copy/paste, it is properly sent: > .HEIC, Live Photo, 4032x3024, 1.1 MB, filename has been changed. --- Why is copy/paste not transmitting the full resolution file? Is there a setting that controls the quality of copy/pasted images from Photos or into Messages?