The show really nuked the fridge in the final season.
nuke the fridge
idiomTo suddenly include a strange or illogical event, often leading to radical and often disappointing changes to the narrative of the film.
Origin
first recorded 21st c.From a scene in the film Indiana Jones and the Kingdom of the Crystal Skull (2008), where the main character survives a nuclear detonation by hiding in a lead-lined refrigerator.
Fans complained that the writers nuked the fridge when the main character suddenly gained magical powers.
The series, once praised for its grounded realism, effectively nuked the fridge by introducing a bizarre, unexplained plot twist that alienated its core audience.