If you are feeding every 4 days - you overnuted the damn thing. Also , what gives about distilled water ?
Run tap - not only will soil work to buffer it / municipal ( city ) water has calcium and magnesium already in it. So by trying to replace it because you are using “ special “ water is unnecessary. Tiger Bloom is the Bloom nute from the trio set. It is highly concentrated so if you are basing dosage from their feed schedule you are guaranteed to overfeed. This is a nute you have to let the plant show what it can tolerate and we started at 1/4 strength to start. It salts up the medium fast .
Also , leaching your soil just to do “ runoff checks “ does more harm than good … as you continue to over water it to get runoff , you unbalance the medium further.
Plus , the most glaring issue is it’s an auto. . Autos do not need complicated feeds. Most bagged soils could carry it along for weeks alone.
Lastly , since you are mid point of flower ( plant finishes when it finishes regardless of breeder estimates ) you only have time to stop further issues , plant will not recover damage leaf. Flower formation can also be impacted by wonky feeding / environment and of course stress ( which can come from your hand - feeding and what not ).