@Anonymous User, this is not a solution to the underlying problem. I am also experiencing this issue with ArcGIS Pro 2.8.1 when trying to clone the default arcgispro-py3 conda environment. Can esri provide an actual solution to this bug?
conda create --clone arcgispro-py3 --name arcgispro-py3-clone
# ERROR conda.core.link:_execute(700): An error occurred while installing package 'esri::arcgis-1.8.5-py37_1783'.