bathos

Overdone or treacly attempts to inspire pathos.

A risible failure on the part of a work of art to properly affect its audience, particularly owing to

An anticlimax: an abrupt transition in style or subject from high to low.

A banality: an unaffectingly clichéd or trite treatment of a topic.

Immaturity: a lack of serious treatment of a topic.

A hyperbole: excessiveness.

The ironic use of such failure for satiric or humorous effect.

A nadir, a low point particularly in one's career.