I am not sure what caused the surface of the uploaded object appears blotchy. Initially I thought the object is “too complex” and I tested it on a simple cube The cube also exhibits the same blotchiness.
Should I have done something in Blender before uploading it to Speckle in order to get a “WYSIWYG” appearance?
I checked out you file. The reason why you’re seeing the “blotchiness” is because currently we’re not treating “hard edges” properly and this breaks normals on planar surfaces. When faces share vertices, when we compute the normals the result get weighted against all connected faces.
This issue has been raised several times and we are planning to find a suitable solution, but until then you can avoid it by using the Edge Split modifier in blender on surfaces with hard edges.
Here is your model with the edge split modifier applied. The blotchiness is gone.