Championship leader Verstappen collected two reprimands for three incidents reviewed but escaped any penalty for Sunday's race at Marina Bay.
Media reports said Matteo Perini, the only one of the four Singapore stewards who is also carrying out the role at this weekend's Japanese Grand Prix, had recognised the mistake at a meeting with team managers at Suzuka.
An FIA spokesman confirmed the matter was discussed.
Verstappen qualified 11th but was summoned for impeding AlphaTauri's Yuki Tsunoda (23) and Williams' Logan Sargeant (22) in separate incidents. The former's team, also owned by Red Bull, did not send anyone to the hearing.
The offence would normally have incurred a three place grid drop.
McLaren's Lando Norris (23) said on Thursday that drivers should face harsher penalties for impeding and questioned why Verstappen had escaped a drop for the Tsunoda incident.
Mercedes' George Russell (25), a director of the Grand Prix Drivers' Association, also said the wrong decision had been taken.
"It doesn't matter if you're leading the championship or you're last, if you get in somebody's way you should be penalised for it," he said.
Alpine's Pierre Gasly (27), who collected two grid drops at the Spanish Grand Prix, was also confused.
"Maybe now this is allowed. I don't know, I'll ask," he told reporters on Thursday.
Singapore dealt Red Bull their first defeat in a season of dominance and also ended Verstappen's record run of 10 wins in a row.
