if you add issue number in Bugs: list in right side pane, then the issue is one click away:D
11051 zfs miscounts BP_IS_EMBEDDED blocks during scan.
Review Request #1849 — Created May 20, 2019 and submitted
This is work by Bill Sommerfeld. There is a new ZoL PR which was created based on the illumos bug report and suggested fix. I've also included the comment from the ZoL PR.
Reproduced before and after the fix, notes in the bug report.