Jason Schreier, a reporter for Bloomberg who has broken some major stories in the gaming industry, revealed in a Reddit AMA that Netflix and Blizzard were developing an Overwatch Series, along with StarCraft and Diablo, before Activsion-Blizzard and Netflix had a significant fallout when the latter poached their CFO.

Sources:

https://www.reddit.com/r/wow/comments/1fs5nw9/im_jason_schreier_reporter_at_bloomberg_and/ 

https://variety.com/2020/tv/news/activision-blizzard-sues-netflix-poaching-spencer-neumann-1234846539/

https://www.pcgamer.com/games/fps/overwatch-2-players-are-banging-their-heads-against-a-wall-after-finding-out-that-blizzard-fumbled-a-netflix-adaptation/