In the article, they say that electricity has gone from .29 to .45 euros, a 55% increase. If electricity was the dominating cost, seems like they would have raised the price way more than 10%.
So the electricity is not really dominating the costs, but it might still be the largest component of the cost.
There is an estimate that Amazon has a 61% profit margin for cloud services. Hetzner must have a lower profit margin, but nonetheless the electricity could be as much as half of the costs.
Where are you pulling seeing the price change %? I may need to edit that to marginal, if it's only 10%. :)
electricity/air conditioning rate old price* new price*\
Germany € 0.29/kWh € 0.45/kWh
Finland € 0.12/kWh € 0.22/kWh