ring hollow(для кого-либо – to someone: Threats that the west will help Ukrainian resistance in the event of occupation may ring hollow in Moscow, given Russia’s 100% success rate in suppressing resistance movements of this kind.theguardian.com4uzhoj)
hot air(things that someone says that are intended to sound impressive but do not really mean anything or are not true: The theory was dismissed as a lot of hot air. LDCE Alexander Demidov)