So Renault have had an updated MGU-K available since Monaco, but since it's packaged differently Red-bull, so far, refuse to use it - maybe for penalty reasons also who knows. Renault and Mclaren(Stoffle only) have been using it since it was available and have had no issues with it so far. This is lighter, more durable and brings slightly better performance - it's the one that they have been waiting for for ages.
Also Red-bull use a different fuel and oil to the works team and Mclaren, the oil is used for lubrication and heat management, so it's down to red-bull to make sure they have this right - nothing to do with Renault. Sure, some failures may not be down to any of it but it's hard to know when you are not using the lubricant the engine was designed for or the fuel the engine was mapped for. I'm 99% sure that Red-bull will have to be altering the engine map to a small degree to account for the change in fuel - but that will have little no no effect on an MGU-K failures.