When exporting a feature class from FGDB to SHP you will get this warning if the FC has attachments.

Please fix the message to say "Attachments are not supported in Shapefiles".
The current message may confuse less experienced users into thinking there is something wrong with their geodatabase.
In case you were thinking to say that a Shapefile is a form of a geodatabase - No. Just No.
Even if it may be by some technical definition after consuming a lot of red cordial, it is not. 🤣🤣