In PCBNew DRC a warning is flagged if certain attributes of a footprint are not the same in the library as on the board.
This is usually quite useful because you may have updated the footprint without updating the board, etc…
However, Fabrication Attributes are the sort of thing which can be decided “on the fly”. For example, one might call for a prototype area on a board in the schematic and, if there is room over, add another on the PCB.
The reason I mention this is that it took me a while to track down why I was having the warnings despite updating the footprint. Only when I essentially asked to reset all fields did the warning go away.
If there is a warning, perhaps if could be flagged as “Fabrication attributes do not match library” or something to help the user narrow it down.
If warnings are too broad they will tend to be ignored.