What is the best way to report it to Apple for them to take a look at it?
I did not see Apple provide a "public"-forum-like platform for report bugs. I reported the problem with Safari's handling of the Clipboard.
It became somewhat like AppleCare support. The communication is only me and the engineers via a customer service representative. The representative was friendly, responsive. But I don't think it is the best way to handle bugs/or bug-like issues.