Hi,
Please see my stack exchange post:
https://gis.stackexchange.com/questions/430544/inconsistent-results-between-gdalwarp-with-cutline-and-rasterio-mask
and this post: https://github.com/rasterio/rasterio/issues/2355 which seems to have noticed this same issue.

On closer inspection, rasterio adds about an extra row of pixels (see attachment), which would seem to be incorrect.
Purple shows the vector I'm cropping to; the black is the result of the gdalWarp and the red is the extra from Rasterio.

Thanks!