When the Aggregate Polygons geoprocessing tool is executed in ArcGIS Pro using the WKID 3006 projection, the specific distribution of polygons generates erroneous output.
The issue only occurs in ArcGIS Pro 2.8 and above (through 3.1.2) and is not reproducible in ArcMap 10.8.2 with the same workflow carried out.
If the input data is projected from WKID 3006 to WKID 3857, the output polygons are not corrupted in ArcGIS Pro. This issue is specific to the WKID 3006 projection.