Keeping brand traffic out of PMax - what is actually working for people?

Our PMax campaign is eating brand searches and reporting them as its own success. Cost per conversion looks fantastic, which is exactly what you would expect when a campaign takes credit for people who were already coming. Brand exclusions are on. They help and they are not airtight - variants and misspellings still get through, and anything that's not literally the brand name but is obviously navigational does too. What I want to know is whether people are solving this with exclusions, with a separate brand search campaign that outranks it, or by accepting the blend and only ever looking at non-brand performance separately. Every option has an argument and I would rather hear what people are living with than what the theory says.