OP,
Whoever said that was not precise about it.
GT model has iEloop, which uses AGM battery that works with a super-cap.
Replacing the 12V AGM battery needs programming. Otherwise, you might get warning lights on the dash or other strange issues.
For non-GP model (e.g. your Sports), you can DIY.
I know it because I have a '16 Mazda6 GT that demands that.
The battery goes every 3 yrs or so.
$400-$500 to replace (including programming) at local dealers in SF bay area.