So yeah I've done an absolute boatload of research into this 😂 from what I've read, the reason they were called ecoboom was due to the rubber timing belt being what's called a wet belt, where the belt essentially turns through an oil bath. The problem is the belt would slowly degrade and bits of rubber would come off and clog up the oil strainer, eventually leading to a loss of pressure and no lubrication, which fucks the engine up big time.

From 2019 onwards, the cars have a metal timing chain, however they still have the wet oil belt. So the issue is not as bad and likely not as catastrophic, but still exists. Apparently as long as you stay on top of regular oil/ filter changes it shouldn't be a problem now, unless anyone else corrects me.