Yes, the Imagery Basemap from AGOL. I didn't realize that the service layers were optimized at 96 dpi.
"Issues may arise when attempting to print or export maps with service layers, as the map printed is in low quality. Most cached web map services such as those available from ArcGIS Online are designed for viewing on the screen at this resolution and are expected to print at a lower quality because the services are not designed for printing at higher quality. The basemaps are provided as services, thus such behavior is expected."
Thank you for answering my curiosity George Thompson!