Hi Pierre, old fellow!
For your information, the IV./JG1, then I./JG1 "Teufel in den Wolken" emblem was already depicted with "yellowish" background instead of blue in serie "Jagdfliegerverbände der deutschen Luftwaffe" (Vol.7 + Vol.10/II) already from 2008 on.
But, that said... the devil always hides in details!
It is an old emblem inherited from 2./JGr.101, where it was sported on both sides of Emils during the Sitzkrieg (crest background is also depicted as yellow in Vol.2).
For IV./JG1, on both sides for Emils, and on left side only for FW's (Vol.7).
For I./JG1, on both sides fo