I’ve never been keen on these characters, and unfortunately, this film doesn't surpass the rather unbelievable, physical comedy cartoon from the nineteen seventies. It begins with an explanation of how the younger version of "Shaggy" and his dog companion initially met, then moves to a modern setting where they, along with the rest of the "Mystery Inc." team, have to collaborate to stop a scheme meant to release the mythical protector of the underworld—a ghostly version of Cerberus—upon the world. To its credit, it doesn't waste any time, and the animation style stays true to the original television show; however, the script is weak and corny, and for me, the characters are simply annoying, relying on predictable tropes. The endings were always somewhat ridiculous, and that remains consistent here—it’s all too trivial and disappointing. I would have supported Cerberus without hesitation. It may be targeted at adults who remember it with more affection than I do. Regardless, I don't think this will appeal to children currently, and perhaps the restrictions of lockdown actually did us a favor by preventing its release in theaters.

Source on TMDB