If decission is made means you are approved and will get ppr soon, you dont need to be worry about rejection because in case if they are going to refusal they send PFL and give opportunity to proof relation or respond.. so just wait for ppr everything will be ok..
This is not true I know couple of people who got rejected recently after Decision Made. They didn't get pre arrival though no interview and no PFL either. IRCC stated relationship is not genuine.