Fit inside not working as expected

[nagman]

I have this image:

Which, when resized through this url: http://localhost:3000/_ipx/f_jpg,fit_inside,s_1800x2700/img/test.jpg, outputs like this:

Note that it's using fit_inside and s_1800x2700.

I don't understand why, but I wonder if it's related to how the inside fit is calculated.
Because no matter how many zeros I add to the size, it'll stay at 111 x 38 in the output image.