Mercedes team principal Toto Wolff accepted full responsibility for the setback, admitting the team had let Russell down.
He said the Briton had endured too many reliability-related issues this season and stressed Mercedes was working to eliminate the recurring problems.
“Both drivers put in strong races today. Kimi did well to get onto the podium and P3 and George did brilliantly to fight back after the opening lap,” said Wolff.
“His problem at the start was fully on us as a team and it isn’t good enough.
“He has suffered too many of these problems; we are doing everything we can to get on top of them, but it is unfortunately another issue that has cost him again today.”
Russell’s fightback limited the damage in the Drivers’ Championship, although he heads into the summer break 59 points behind teammate Andrea Kimi Antonelli.
“We nearly got very unlucky with yet another ill-timed Virtual Safety Car, but Kimi defended well to hold off Lewis (Hamilton),” added Wolff.
“It was good damage limitation after a difficult day yesterday.”
Antonelli continued his title charge by claiming third place at the Hungaroring after Mercedes made a decisive strategic call. The team had originally intended to complete the race with a one-stop plan before excessive tyre degradation prompted a switch to two stops.
The revised approach left the championship leader on fresher tyres than many of his rivals in the closing stages. Mercedes also benefited from the timing of the late Virtual Safety Car, allowing Antonelli to stay out while others pitted.
After the restart, Antonelli resisted sustained pressure from Ferrari’s Lewis Hamilton to secure another podium finish.
