Max Verstappen's father does not think Ferrari made a "calculation error" with the fuel load aboard Charles Leclerc's car in Abu Dhabi.
Ferrari escaped with a EUR 50,000 fine for under-declaring to the FIA the amount of fuel that was aboard Leclerc's car for the race start.
Earlier, Max Verstappen accused Ferrari of "cheating" in 2019 with its power unit.
And now his father and co-manager Jos has told Dutch commentator Olav Mol on Ziggo Sport: "Olav, you know it wasn't a calculation error.
"I am not going to talk too much about it, because it is a very dangerous subject in Formula 1. I don't want to burn my fingers on it.
"But next season the rules must be tightened," Verstappen snr added.