Prose craft
Bathos
An abrupt transition from the elevated to the ridiculous, a ludicrous descent that reads as a failure of tone unless meant as comedy.
Bathos is an abrupt transition from the lofty and elevated to the silly or trivial, a descent that lands as ludicrous or comic. The Greek bathos means "depth," coined as a mock opposite of pathos, "height," and Alexander Pope launched the term in Peri Bathous, Or the Art of Sinking in Poetry (1727), a prose parody of Longinus cataloguing his rivals' grand thoughts puncturing themselves. Modern usage covers both cases: unintentional bathos, seriousness failed through ineptitude, and deliberate bathos, a rhetorical device for comedy in satire, burlesque and mock epic. The article ties the accidental kind to the anticlimax and to camp; its image of failed seriousness is a filmmaker presenting "a man in a gorilla suit with a diving helmet" as scary.
For a writer it is the tone failure to proofread for: elevated style meets a trivial object and the paragraph laughs at itself. Overwrought writing is the usual culprit; see purple prose, and the anticlimax it shades into is noted under climax.