Colored HVAC Badge

Dear all,

re-activating and re-working part of the heating (welcome winter), I realized a colored HVAC icon while this has been white before:
I could not find any spec about this: Semantic Model | openHAB
In principle I anyhow would like to use a icon matching to heating (not cooling) or at least red color for my switch item.
Any background explanation for this blue icon as well as an idea how to get a proper heating icon / color?

Thanks and best