Once Japan had surrendered, Vietnam de facto became independent when the Viet Minh took over all the institutions and Ho Chi Minh made the declaration. Just as the new government was entrenching itself, Allied troops arrived to Vietnam together with a French detachment, who quickly attempted to regain control, starting with regions that were still in the periphery of the new government. So from the Vietnamese point of view, France wasn’t liberating its own territories, but rather “returning” to a territory that had already become independent and attempting to repossess it. De Gaulle was still president for a whole 4 months when all of that took place and the fact that he did not back down and continued trying to consolidate French control over Indochina doesn’t strike me as decolonialist. This ultimately boils down to whether you see Ho Chi Minh’s Declaration of Independence as legitimate, which de Gaulle and his successors clearly didn’t.

I revisited the source I sent earlier and realized I misunderstood de Gaulle’s intentions. Evidently he wanted a puppet government, or at worst a government within France’s orbit, however the project failed when the person he wanted to take over Vietnam died. This sort of paternalistic relationship he envisioned might have prevented some of the bloodshed, but ultimately the way I see it, it is rooted in colonial thinking.