JOON is The AirFrance union breaker operation, However all flights retain the same AF flight code and tickets are still sold with full connectivity beyond Paris.
All flights should be with the A320 with the same CY174 as mainline indeed they are the same aircraft that have regularly operated as mainline until recently.
As Joon aren’t getting any 319 or 318 capacity may actually increase with this move.
Its rather like Iberia Express being a virtual airline within an airline.
Quite a lot of the AirFrance European secondary routes not in the hands of Hop are likely to be transferred in the medium term it’s part of the plan to make AirFrance more profitable.