I have an asset package supplied from a customer that I have deployed to my Enterprise v10.9. While using ArcGIS Pro v2.7, I staged a utility network, applied the asset package, and shared as a web layer. Before I published, I ran the analyzer and received the following warning for several layers:

The odd part is that the layers that produce this warning are not the layers that are being converted to picture markers and giving me a problem. The customer has created symbology that involves multiple, shape marker layers. E.g.

When I go to my Portal and open the feature service via ArcGIS Pro, the same image is now converted to a picture marker after deployment. E.g.

I have taken my Naperville test deployment, and changed some of the symbology for features to match that of my customers, including the one shown in the example above. When I redeploy Naperville, those custom symbols I created are not converted into picture markers and retain their multi-layer shape marker format. Is there any specific setting that triggers the conversion of symbols to picture markers? I find it odd that replicating the symbols, even matching all their property settings, still achieves differing results between my test Naperville and my customer's asset package.