At the end of the recent 'test-gate' hearing, the FIA tribunal banned Mercedes from attending next month's test for rookie drivers at Silverstone.
But Red Bull's Dr Helmut Marko said that is hardly a penalty at all.
"You can't really try anything in the young drivers test," he said.
"The drivers at the wheel are just learning about Formula One, while Mercedes had three days (in Barcelona) with their regular drivers."
However, team boss Brawn has hit back at Marko's claims by insisting that missing the test is in fact "significant".
"To downgrade the test and to make out it is not significant is not correct, and just an attempt by teams concerned to distort the facts," he is quoted by the Telegraph.
"I think we have a very tangible loss."
Brawn suggested missing Silverstone will not simply equalise Mercedes' advantage of having run with race drivers Lewis Hamilton and Nico Rosberg with the 2013 car at Barcelona in May.
"It is a different league quite frankly to have a three day test, over 1500 kilometres, with new parts, with race tyres that are those we race," he said.
"It is unfortunate the spin that some teams are putting on the punishment that it is not significant."
Brawn's view is even backed by Jonathan Neale, the managing director of the similarly Mercedes-powered McLaren team.
"With the paucity of track testing that we have at the moment, missing the young driver test is obviously problematic," he told reporters in a Vodafone teleconference.
"They (Mercedes) will be sorry to miss it."
Nonetheless, even serving the 'test-gate' penalties will likely not end the finger-pointing at Mercedes, with Hamilton admitting that a good result this weekend will be inevitably traced back to the highly controversial test.
"People will jump to conclusions I am sure," he is quoted by British newspapers.
"We have had a couple of positive races because those circuits have been easier on tyres. That's just made it look like we have had a benefit from the Pirelli test," added the 2008 world champion.