MIL feeding baby

So we left our almost 3 month old with our MIL and I mentioned to her that we pace feed our daughter since we exclusively breastfeed her( she takes bottles too but primarily breastfeeding). We also give her 2oz bottles at a time( she’s normally pretty satisfied maybe she’ll extend to 4 but very rare) and she typically eats every 3 hours

Anyways she was telling me that she ate 12 oz in a 4 hours period!! I was so upset that she just kept feeding her and feeding her. Then she said she slept through the might and I’m thinking in my head”yeah you fed her so much”

I don’t know what to do, I want to tell her something cause she’s going to be watching her again in a couple of weeks(not overnight but for a few hours)

How did you handle this? Thank you in advance!