seperate feeding & moving to "adult" food

So, i brought my now 7 months old 22kg puppy when he was 2 months old. I have another 9kg adult dog and they eat twice a day. until recently, i just told him "go to your place" and he would run to his fence and wait to eat there.
now we got rid of it, and he is really not a fan of eating in our bedroom and will cry to go out a lot, he usually eats the bare minimum and then stops, if i stay with him the whole duration he would usually eat in little pulses but the average has really went down this recent week, is it normal or is there a better solution?

also, another reason its even more important for him to eat in isolation is because they receive different food. my adult will never try to eat the puppy's food, but the puppy really gets distracted and sometimes will even try to get to the adult's plate which botheres him.
ive read online that for dogs his size its usually normal to switch to adult food at around 1.5 years, but they are both being fed taste of the wild, which as ive understood used to be food for all ages? so maybe its fine to put him on the "adult" food earlier?

thanks!