His apology sounded like a false note.
false note
idiomOf a remark or narrative, an indication (as discerned by the listener or reader) of untruth, insincerity, or inconsistency.
The politician tried to sound sincere, but his promise to lower taxes struck a false note with the crowd.
Throughout the entire memoir, the author’s sudden shift to a tone of humble regret struck a false note, suggesting he was merely trying to manipulate the reader’s sympathy.