Yea, overfeeding, autos need so much less nutrients than a photoperiod plant, i grow mine in
ffof, since your not giveing nutrients your mix must be very hot, allso with autos it is not uncommon for the leaves to yellow a bit at end of grow, northern lights is a tuff strain that lets most beginner mistakes slide, but if your only giveing water your mix is probably to hot for autoflowers. But they realy dont look that bad at all and i almost allways burn my tips in flower bc this tells me my plants are at maximum nutrient uptake, i dont burn leaves just the tips, i dont really like nl but thats just me here is a pic of 1.