These latest Red Bull concerns come after the constructors' champions also recently lodged an unofficial request with the FIA regarding the legitimacy of Mercedes' new front wing.
That recent Mercedes upgrade looks to have brought Toto Wolff's team back into contention for race wins, after a season's-best P3 and P4 finish in Canada marked a missed opportunity following George Russell's pole.
Red Bull concerned by Ferrari, McLaren and Mercedes
Only last summer, the FIA issued a mid-season technical directive which sought to clamp down on flexible front wings. Red Bull have already noted their concerns with the flexibility of the new Mercedes front wing, which passed the FIA's static tests and the team now have Ferrari and McLaren in their sights.
AMuS' Michael Schmidt reports that Red Bull now believe both Ferrari and McLaren's front wing is bending more than it should under the corresponding load.
Schmidt also reports that Red Bull had wanted Aston Martin to protest these wings, but that they themselves are working on a similar solution for their own car.
Interestingly, Schmidt also reports that Mercedes were also suspicious that the front wings were largely responsible for McLaren and Ferrari's pace. However, rather than protest, Mercedes have instead sought their own similar solutions.
Despite the above, Red Bull maintains a healthy lead at the top of both the drivers' and constructors' championships.