Pal. There wouldn't be a change within mins, let alone hours.
You will have to look to new growth. As growth that showed signs of defs/toxs will stay like that long after the problem is gone
Look to new growth for new problems. Old growth old problems leave em where they belong in the past. You plant needs some bloom boost that's all. Them leafs will get lighter as they'll be a source of food so don't take them or the plant will move to other leafs for what it needs.