Can changing a dog’s eating habits/schedule make them get sick?

Sorry in advance for the large text post:

For context, my family has three bigger dogs: a female rottweiler (6), a male rottweiler (10), and a pound pup (also estimated to be about ~10).

I’ve been out of my family’s house for about 6 months now and just came back home to visit for a few weeks over Easter. Over the span of these six months, though, I’ve been told that our older boy, Bear (the male rottweiler), has been throwing up consistently.

My family knows I can get stressed out and worried about our pups, so I think they’ve been hiding just how much he’s been doing this. But now that I’m home, I’ve noticed it happening more often than I previously believed it to. After bringing up concerns, my parents just mention that they’ve changed their eating schedule and habits to only two cups at one time during the day.

Nevermind the fact that that is way too little to be feeding large dogs, but changing the feedings to only once a day is crazy. Before I left home, we’d feed our boys 2 cups twice a day, and our girl 1.5 cups twice for breakfast and dinner. Now they’re getting half of it.

I tried explaining that this may be what’s causing our old boy to get sick, but I’m getting blown off and told that “the other dogs are doing fine with the change”. Am I crazy? This can’t be helping him even if it isn’t the core reason of him getting sick, right?

Any help with this would be appreciated- I’m gonna try and keep a closer eye and see if there’s a particular time he does it and (grossly) see if it’s more bile or undigested food. I don’t think it’s the latter namely because Bear has always been a slow eater, but I could be missing something.