According to Disinsider, SpongeBob SquarePants writer Christopher Painter had an Oswald the Lucky Rabbit series for Disney+ listed on his resume online. Information about the project has since been removed, but Painter's resume originally listed him as "Currently writing and story editing a new 13-episode series for a major streaming service to be announced soon."
At this time, Disney has not confirmed the project, so it's possible it will be announced soon or even never materialize.
Created by Walt Disney and Ub Iwerks, Oswald the Lucky Rabbit first appeared in 1927's Trolley Troubles, becoming the first animated character from the then fledgeling House of Mouse to receive his own series. After a battle with Charles Mintz and Universal Studios, which originally distributed Oswald's shorts, over the character, Disney and Iwerks created Mickey Mouse. Disney didn't regain rights to the character until 2006. The character has since appeared in such Disney products as the video game Epic Mickey and returning to animation in the 2013 short Get a Horse!.