I have recently learned how to script my web layer updates using the arcpy.sharing module. This is great, as I can update my parcel data every morning. However, every time the script runs, the thumbnail on AGOL is replaced with a generic one. I have a thumbnail specified in the aprx map, but it gets overwritten unless I publish directly from Pro.
Now that I am publishing my data in a data hub/open data site, this lack of a proper (custom) thumbnail matters. I don't want to have to reupload my thumbnail every day. I would like a property for getWebLayerSharingDraft to specify a thumbnail, as you can do with the summary and description. For my use case, the following idea would also work (the ability to create a default overlay for a thumbnail, with branding). Create default overlay for thumbnails