10075: Layer's data source has a different projection <value> than the map's projection
The named layer is in a different coordinate system than the coordinate system of the map or scene. This requires on-the-fly projection, which can affect drawing performance. The <value> parameter of this warning message indicates the projection of the data source.
Solutions
Review the draw metrics for this layer. If you are sharing the layer, review the data access metrics for the service, as well.
Learn more about performance in ArcGIS Pro
If it appears on-the-fly projection is impacting draw performance, do one of the following:
Change the projection of the map to match the projection of the layer. For more information, see Work with coordinate systems.
Project the layer's data source to match the projection of the map. Then change the data source of the layer to the newly projected data. See the Project geoprocessing tool for more information.
Do nothing. In some situations, on-the-fly map projection may not degrade performance. For example, datasets with a small number of simple features (points, line, or polygon features with very few vertices) may display quickly in spite of the need to perform on-the-fly projection.
Additional information
The map's coordinate system does not need to be the same as the data you are using. However, if the map has to project your layers on the fly, it takes longer to draw. If the delay is significant, changes to the map's or data source's coordinate system should be made.