Mother-in-law always on her phone

We leave our LO with my mother-in-law 2 days a week while we work and I’m so grateful for the help. I’ve notice, however, that she’s on her phone a considerable bit. Just scrolling and my LO is trying to get her attention at times but she seems more interested in the phone. When we’re home with our son we try to give him as much of our attention as possible and limit our phone use while he’s awake and playful. I’m very irritated by this because it makes me wonder how much she’s using it when we’re not around 🤔 Should I talk to her about it? Or put our son in nursery? Or both??