There's something of an answer here: https://www.thelocal.fr/20211115/tricolore-5-things-to-know-about-the-french-flag/
TL;DR: This changes it back from a change made to make the blue more like the blue in the EU flag - and it was done in 2018
Written by Bob Koure
Retired software architect, statistical analyst, hotel mgr, bike racer, distance swimmer. Photographer. Amateur historian. Avid reader. Home cook. Never-FBer