The details are unclear, but D&D editor Chris Sims has reported that he is now in need of a job, and is willing to relocate. He was hired by WotC in 2005 after working for them as a freelance editor. Part of the D&D 5E launch, he was one of the editors for the Player's Handbook and Dungeon Master's Guide, and was responsible for stat block development in the Monster Manual. The reasons have not been revealed, nor is it clear whether he left or was laid off.
Whether this is an isolated thing or part of more layoffs if unclear right now. More if I hear anything! In the meantime, if you can hire an excellent writer and editor, please do!
For more on ex-WotC employees, please check my list here!
UPDATE: Jennifer Clarke Wilkes is also in the same boat. She has worked on both D&D as an editor and on Magic: the Gathering, and has been working for WotC for many years.
UPDATE 2: Chris Sims confirms here that he and Jennifer were both laid off.