Perez started the Melbourne race in sixth after picking up a three-place penalty for impeding, and having lost a place to George Russell at the start he recovered to finish fifth.
He reported that the balance didn't feel right but it was only after the chequered flag that the team discovered that the tear-off had become lodged in the floor of the car.
"We went long on the first stint," said Red Bull team principal Christian Horner. "And his actual pace when he was coming through the field on the hard tyre as he closed in on Fernando was strong, and matching that of the leaders.
"And then literally as he's passed Fernando, he's picked up a tear-off underneath the floor and it's got lodged in an area that's caused significant load loss.
"So as he's then passed Fernando, the car's not working as it should. And so then you start to see degradation on the tyre, and again at the end of the second stint, which has been unusual for our cars."
Regarding the impact on downforce, Horner added: "I think it was in excess of 20 points. So it's a significant amount. It just shows how sensitive these things are."
Asked by Motorsport.com if Perez could have challenged the Ferraris of Carlos Sainz and Charles Leclerc had he not had a three-place grid drop, Horner thinks that the Italian team probably still had the edge.
"Difficult to say," he said. "I mean for sure he's been compromised when he's picked up the issue with the floor. I think they were maybe just a bit, maybe a bit too quick today, but you never know."
Perez suggested that the Albert Park track simply didn't suit Red Bull.
"I think it's probably tarmac-related," said the Mexican. "If you remember Vegas, we were already struggling last year.
"So I think there's something in it that. We just have to make sure we work hard to try and understand what the issues are.
"I think today we just didn't have the pace as a team. If you see Max was overtaken within two laps. That already shows something."
