Cancellation announcement (fluffed as "relegated to technology preview): https://forums.freenas.org/index.php?threads/important-annou...
Bug tracker, for illustration. It used to have more than a dozen developers on it: https://bugs.freenas.org/projects/freenas-10
Former developer tweet about layoffs (note date of tweet is 4/7): https://twitter.com/JoshuaRule/status/850460463720800256
And all over r/freenas. The total number laid off seems to be around eight of maybe twelve. One way to check that is to compare internet archive versions of the bug tracker and compare it to developers who no longer commit to any FreeNAS projects as of last month (edit: and who are not on the other FreeNAS bug tracker). The remainder are redirected back to 9.x (soon to be 11).