Mount Blue Sky, was Mount Evans.

That's the story, Mt. Evans in Colorado has been renamed Mt. Blue Sky.

The mountain was named after Colorado Territorial Governor John Evans.  The Civil War era Governor was obviously popular enough at the time, but his association with the Sand Creek Massacre has caused his memory to tarnish over the years.  That association may be noted here:

June 24

1864   Colorado Governor John Evans warns that all peaceful Indians in the region must report to the Sand Creek reservation or risk being attacked.  This set in motion that lead to the chain of events that caused the infamous Sand Creek Massacre, The Battle of Red Buttes, and the Battle of Platte Bridge Station.

The even itself is discussed here:

November 29

1864         Sand Creek Massacre in which Colorado militia attack Black Kettle's Cheyenne band in Colorado.  Black Kettle was at peace, and the attack was unwarranted.  The unit would muster out shortly thereafter.  The attack would drive many Cheyenne north into Wyoming and western Nebraska, where they would link up with Sioux who were already trending towards hostility with the United States.  This would result in ongoing unbroken armed conflict between these tribes and the United States up through the conclusion of Red Cloud's War.

In 2020, current Colorado Governor Polish established The Colorado Geographic Naming Advisory Board which suggested the new name, which was approved by the Cheyenne and Arapaho tribes.  Clear Creek County approved the renaming in 2022.

Evans' reassessment is an example of how such reappraisals have occured post World War Two. Evans was forced to resign as a result of the Sand Creek Massacre and was accused of a cover-up in regard to it, but nonetheless, as late as 1963 he was inducted into the Hall of Great Westerners of the National Cowboy & Western Heritage Museum.  Charitable in many things, other than his views on the fate of Native Peoples, various things were named for him, including Mount Evans, a World War Two destroyer and the Evans Chapel at the University of Denver, the latter of which he had built in memory of a daughter.