It looks like Beeminder is stealing a minute

I entered three data points in the advanced entry form of my goal work. One of them was 6:53.
It then briefly showed up as 6:52 (!) in the list of data points, then it changed into 6.883333333333333. It changing alone is a bug already, but this is not about this. This is about it showing 6:52 instead of 6:53.

Where did the other minute go?

Also, see the discussion about a rational datatype for modelling fractions that are not subject to the whims of the IEEE 32 bit float and JS’ Number datatype: