That’s a pointless title. The truth is that 5.5 people claim they didn’t heat sufficiently. Whether it was objectively sufficient is a completely different question and going by the actual numbers for usage, households Germans barely reduced their heating. Almost all savings were done by the industry. The the average person in Germany still heats their living room above 20°C.
If you’re healthy then going with 17°C indoors isn’t actually a problem (I tested that myself last year). Having to wear a second sweater or using a blanket isn’t something you should get to complain about when the alternative literally kills people.