UPDATE: According to Tim Szabo's website, he was one of the background painters working on this film. While his page just lists the film as "Scooby-Doo Meets Courage the Cowardly Dog," what's interesting is that it shows the film has been in production all the way back since around August 2018. Background painting for this film (and another film, Mortal Kombat Legends: Scorpion's Revenge), concluded in February 2021. Thanks to Ben for sending me this!
According to several release sites in Norway and Finland, the Scooby-Doo and Courage the Cowardly Dog that was announced will be titled "Scooby-Doo! Straight Outta Nowhere" and will be released on September 13, 2021 in those countries. CDOn.no, Platekompaniet.no, and Hinta.fi all list this. I'm not sure of the legitimacy of these sites, but given multiple are listing it, it's possible this is the actual title of the movie. I suppose we'll just have to wait and see!