I honestly think there will be the same 'boost' in qualifying from Mercedes.
The only team that had evidence of extra burning was Ferrari (when the second tank was found). Mercedes have always denied it and even now are saying their Q3 mode is even better than before. They are never the sort of team to play things up like that, they always play things down and say how good the competition is etc.
It only ever seems to be RedBull complaining about extra burning. But then.... don't they complain about most things, especially engine related. They also brought up wanting all teams to have the same engines (per manufacturer) as well. Its like they blame everything on the engines and cannot accept it is ever anything to do with their car.