I have a 2021 Subaru Legacy and I've never had the phantom breaking as well. I've put about 10k miles on the car with at least 7k of it being on adaptive cruise

I have a 2021 Subaru Legacy and I've never had the phantom breaking as well. I've put about 10k miles on the car with at least 7k of it being on adaptive cruise. All of the miles have been on country roads with hills, sharp turns, traffic, inclement weather, etc. I second the suggestion to get it checked.