You have read the information circled-i which say “ This parameter comprises both direct and diffuse solar radiation.
[….] However, care should be taken when comparing model parameters with observations, because observations are often local to a particular point in space and time, rather than representing averages over a model grid box.
Remember that the ECMWF model resolution is 9 km approx. or 5.5 miles, which is the distance between the grid points.
Windy just displays the raw data provided by the weather model which computes the solar radiation. It takes into account the angle of the sun relative to the earth surface, while on the Clouds layer you see the clouds shapes from a vertical view.
When you say “ I guess I didnt expect that to mean YOU wouldnt adjust for relative cloud cover between the measurement site and the map coordinate?”, you’re probably unaware that Windy does not a make any adjustment and that the data is not provided by a measurement site but directly by the weather model.