False Northing used for UTM in geodesy CPP but not in Python

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If I use geodesy in Python to produce UTM coordinates for lat=-22 lon=-43.93, it produces (610450.9538105723, -2433213.3341837334). Note that the northing value is negative. If I do the same thing in C++, it produces a northing value of 7566786.665816266. It's the same value, just with 10,000,000 added to it, which is standard in UTM.

The problem I'm facing is that in my project, our localization system uses Python and our path generation system uses C++. As a result, I end up with points on a trajectory that are 10,000,000 m away from where the robot thinks it is currently. Which makes more sense to change: Python to match UTM, or CPP to not use false Northing?