be careful
it will still represent the full signal, just not with much precision in the low end for analysis. I think loudness will take the energy in all bins, including DC, so it should not change much. you can send test signal to it at different fft and it should not change amplitude - but if you only get a part of a wave, yes, it won’t represent the full energy. that is why they use 400ms for loudness in EBU (but then they have filters to represent roughly equal loudness contour and such)