Red Bull technical director Pierre Waché has confirmed the team's developmental direction has taken the RB18 outside of Sergio Perez's set-up window.
The Mexican was in fine form early in the season and looked to be mounting a title charge as team-mate Max Verstappen struggled with inherent understeer from the chassis.
A win at Monaco, that thrust Perez to within 15 points of Verstappen, also pre-empted a contract extension through to the end of the 2024 season.
But following two retirements in four races thereafter, Perez has been unable to replicate his early performances.
Such has been his slip in form, Perez now trails Verstappen by 125 points after taking just one podium in the past six races.
Asked why Verstappen, who has won five successive grands prix to put himself within touching distance of a second title, had found improvement and Perez had slumped, Waché explained: "It is multiple factors.
"The main factor is clearly the car balance and the confidence with a car, compared to the beginning of the year when the car was a little bit more balanced for him and a little bit less for Max.
"And after the development potential we have put on the car during the season, moving away from that is maybe a part of it.
"Finding a right set-up for him, it is quite difficult, to put him as confident as he could be to beat, or to fight with Max."