Helmut Marko accused Sergio Perez of already being in "summer break mode" before the Hungarian Grand Prix.
The Mexican is third in the drivers' standings and just five points behind Charles Leclerc. Earlier in the season, it looked as though he would be a main rival to team-mate Max Verstappen after winning the Monaco Grand Prix.
But things have not gone so well for Perez since, and he is now 85 points adrift of the other Red Bull racer. That has clearly left long-serving team adviser Marko unimpressed, as he took aim at the 32-year-old for his recent performances and attitude.