Stickers don’t work on Photos without meta data

I’ve noticed than when creating a new Sticker in Messages, only photos that were taken on your device, and/or have associates metadata seem to be usable as Stickers.

Example - I took a screenshot of a photo which I then cropped and attempted to navigate to it through the “+”/ create new Sticker function and wasn’t able to find it. I subsequently took a photograph and was able to find it, suggesting that only photographs with metadata associated with your device can be used.

Is this a bug or an intentional feature; perhaps, for privacy reasons?