Extra annoying: enabling eco mode (the one that is tested when generating the power usage stats on the sticker for these machines) on some machines will make it run "60 degree equivalent", which usually means "longer but at a lower temperature", which obviously doesn't work for sterilization at all.
Of course, this is rarely an issue for consumers who don't need to sterilize their clothes (except when a family member is sick with some specific illness maybe?). But, for hospital workers, which this paper is about, that's a different story.
Lower temperatures (e.g. 30-40 degrees C) may even provide a better environment for bateria and/or viruses to grow.
The 90c cycle is the only one I fully trust to get proper hot but I can't wash everything at 90
Still, maybe a failed machine is still a valid test - how many hospital staffs machines are unknowingly faulty?
A quick fix would be to swab staffs clean clothes every so often (or put a test patch in with their washes?) and check it.