This is a regression against gimp in at least bullseye:

If I save a PNG file and disable all metadata, like in the
attached photo, then use sng and less to look at the result,
it still does contains metadata:

The cHRM, gAMA and sRGB chunks are regressions against older GIMP.
Used to it would apply these settings and store just the IHDR, the
PLTE when needed, and the image data.