As with many of Marvel's films, corny scripts have corrupted otherwise excellent films. I guess multiverse of madness falls into that category, except direction saved the film from a complete disaster.
The special guest appearances came about during the reshoots, reports claim. However, their presence did not contribute anything meaningful to the story. It was as if they appeared for the sake of appearing.
Michael Wardon did a great job on the Loki Show. However, it is unclear what led to the screenplay getting bogged down. It might be reshoots, shorter production times, or studio interventions. Whatever, the screenplay ended up being vapid.
The film left things hanging as an open-ended narrative for future installments rather than trying to achieve an overarching narrative. As in, The movie leaves the viewer in the dark rather than trying to explain anything.