I leave it in the laundry, but is it okay to soak it overnight?
Once the dirt comes out of the cloth, won't it return to the cloth if left for a long time?

Answer

I've only left it on for 2 hours, so my predictions are based on experience, but I don't think it will be a problem.
Even after 2 hours of soaking, the color of the T-shirt tag and brand logo did not fade.
However, if you use it for more than 1 hour, the cleaning power and bleaching effect will gradually decrease depending on how dirty the laundry is and the container.
The reason is that the thinner the container and the wider the area, the more surface area comes into contact with air, and the faster the pH value decreases.
In other words, if you reduce the area exposed to air and place it in a vertical container, the pH value will decrease more slowly.
If you can seal it with a lid, the pH value will not drop easily and the cleaning and bleaching effects will continue even overnight.

Also, once removed, stains will not re-adhere to clothing or fabrics.
This means that clothing, cloth, and dirt are also charged with negative electricity and repel each other, so once the dirt has fallen off, it will not re-adhere to clothing or cloth.

postscript

I did an 8 hour soak test.
The laundry items include a dark Uniqlo Airism, a rag that won't remove the stain, and Puma windbreaker pants made of nylon fabric that won't get rid of the smell of disinfectant from farming.
I diluted it 100 times, which is what you often use.
As a result, I think the pH will be less likely to drop if there is a lid.
However, if there is a lot of dirt, the pH will drop while decomposing the dirt.
This time's pH result: 12.18 ⇒ 11.71 Although there was some dirt, I think the reason why the pH only dropped by 0.47 was due to the lid.

The underwear I tested was Uniqlo's AIRism, and I was preparing to throw it away because the fabric was noticeably damaged, darkened, and yellowed.
The result is hard to tell from the photo, but it's not pure white, but it's still wearable.
Attached photo above: Taken out of drawer (I had 2 pieces, so I left only 1 piece for comparison)
Attached photo below: Dilute it 100 times and let it sit for 8 hours before washing (washing for 9 minutes, rinsing once).Drum type.

This is a test to see if dirt will re-adhere to the fabric after 8 hours.

The rag hasn't changed that much, it's just gotten softer.

I was able to get rid of the smell from the windbreaker and there was no discoloration of the metal.
It's hard to tell because it was used for agricultural work and has some scratches ^^;