I had a close in-law that had a total braking failure with their ~2017 Mazda Cx-9, which was one thing, but then the dealer was pretty horrible about acknowledging or even diagnosing it. In the end, they sold it off early instead of continuing to own it with the unknowns on the brakes. So it's an anecdote, but one that makes me look pretty seriously against Mazda - though maybe it was more the dealer than the company.
It's hard to say. Of course the OEM should care what their dealers do and how they treat customers, but ultimately the dealers decide how they are going to handle things.
I haven't had any failures on any of our Mazdas so far (2013 CX-5, though only had it for 2 years. I change cars like clothes, 2014 CX-5 - spouse had for ~70k / 6 years, 2015 Mazda 3 - had for 27k / 6 years). Only issue I had was a battery that died during the pandemic, and it didn't really die - I was able to nurse it back to health and then it kept working through when I sold the car 3 years later. All that to say, I haven't been able to test our dealership with a major failure. But the buying experience did exceed what we experienced at the other dealerships we visited (Hyundai, Chevrolet - lots of unwanted sales contact and in person pressure.)
Honestly it could have been something as simple as a a missed bleed of an air bubble in the brake lines. But this was on a less than 3 yr old car, and its been a while since we last discussed it, & I don't recall if they had any sort of brake service where that would be a possibility - either way after a scare like that, one expects your car maintainer (in this case the dealer) to be open to a bit of diagnostic work - even if only to maintain good relations for future purchases.
