I think they don't treat the vachetta anymore to cut production costs & garner more profits. Lots of companies are doing this nowadays.
Vintage items made by the French Company for LV used a treated smooth-grain leather or pigskin (really!). LV used a treated smooth-grain leather and a treated cross-grain leather for the Mono Papillon (until about 2003/2004 for the latter), then they were made with untreated vachetta like the other Mono items.
I think they don't treat the vachetta anymore to cut production costs & garner more profits. Lots of companies are doing this nowadays.
^^ Azur from 2008 is untreated leather for sure. If carried a lot the vachetta will get a tan quickly though.