Renault says Racing Point's so-called 'pink Mercedes' tactic with its 2020 car is a "slightly concerning" step for Formula 1.
Racing Point drew inspiration from Mercedes' 2019 design when developing its RP20, and the new car has shown impressive speed so far in pre-season testing.
But while Racing Point is adamant it has done nothing against the regulations, rival Renault thinks there could be big implications for F1.
Asked by Autosport if his team was comfortable with Racing Point's approach, Renault's executive director Marcin Budkowski said: "I think it's a slightly concerning evolution for the sport.
"It's a trend that started a few seasons ago and it is a new chapter in that trend.
"It will be for the FIA to decide whether it's fully compliant or not. So at this stage, I don't think I have any more to say."
Budkowski's view was backed by James Key, though the McLaren technical director insisted his outfit wanted to focus on its own performance for now.
"I agree with Marcin's point on that," said Key.
"Of course we look at our competitors, and it's fairly clear what is going on with some of the similarities that you see.
"But our priority is ourselves. We're looking at where we are and concentrating on ourselves."
F1's parts-sharing rules are changing slightly for 2021, but Budkowski is not convinced it will stop teams from forming close alliances.
"The regulations have evolved slightly in terms of what is called transferable components, or what teams can share in terms of IP or sell in terms of parts," he said.
"I don't think it changes completely the question.
"It stems from things like people sharing windtunnels. "It's going in the right direction, but it doesn't prevent everything that you see."