What’s causing this plant’s leaves to look like this?

Hey man, Most growers will not train autoflowers because well they just dont grow like photoperiod strains. Any stress you cause her could possibly add weeks onto your harvest time and impact the size and yield of your plant. good rule of thum with autos is to grow them and just feed them and watch them explode no defoliation or hst as this will slow them down. though this is your property your possesions you can do what the hell you want its your plant but if you want her growing fast and healthy untie her and leave her be. :) the yellow leaves could be a sign of nitrogen deficiency as the top leaves are not effected so thats what I would shoot for maybe give her a diluted feed but not too much as autos are notorious for not needing much at the start and then growing very aggresivly in the first weeks of flower :) Anyhow good luck and Im sure whatever you do shell make you proud :) oh the yellowing could also be down to stress you caused while transplanting and training its not unheard of.