I think it is this bug: https://gitlab.gnome.org/GNOME/gimp/-/issues/5509
Rotating the brush introduces (semi-)transparent pixels, which show black especially over the white quarters.
I tried all ways, hard edge brush, anti-aliased brush, all the precisions, all the modes, without success.
Rotating the brush introduces (semi-)transparent pixels, which show black especially over the white quarters.
I tried all ways, hard edge brush, anti-aliased brush, all the precisions, all the modes, without success.