What gives you the idea that GA will increase growth.

what instructions were you following.

Can it poison the plant and the peppers.

can it cause cancer.

What do you know about GA.

I have used GA-3 on my peppers for years,,Your plant will recover.I had cucumbers do the same thing you are talking about and they stayed stunted for a couple of months and then the new growth took off,
I have learned mainly from trial and error on the amount of GA-3 to use.,,and 500ppm is too strong ,thats why your plant curled.400ppm is the strongest you ever want to use ,and 300ppm is perfect for me.
I also dont use it on plants with less than 6 true leaves.

You can dwarf some plants in juvenile growth stage with GA...

Use it when the fruit is setting or close to that time.

By the way...GA can be used for a lot of purposes, but honestly...if seed elongation in seedlings is desirable you can do that cheaper moving your lights away. It can also help germinate hard-coated seeds and other "tricks."

The most cost effective application of GA for peppers would be in increasing fruit mass, though...and I imagine that's when you'd want to use it.

...and to gdwag, it's considered safe and widely used in the tree fruit industry.

GA-3 is used as an aid to breaking dormancy in some kinds of plants. The seeds are treated and it is not normally used beyond that. An undesirable side affect can be elongated seedlings with reduced viability.
I have Norman Deno's books and he found no effect with peppers. I ran my own tests and found no statistical difference either.

GA is not to help pepper seeds germinate.

What happens is that a normal seed makes a little GA for itself and then gets wet and germinates. But there are 2 cases. One case some seeds wait a long time to make the GA. an example might be a hard seed with solid outside. like a walnut etc. Since the seed might not germinate for several years the GA is not produced. So a GA treatment can help.

Case 2 is when the seeds are old. The pepper seeds might form GA immediately and then after years of sitting around the seeds will not germinate. They are old seeds. But actually if you give them the right GA they just might germinate. The idea is that the GA produced early dried out and is gone. So GA now helps again.

There are some valuable tree seeds where it is worth it on a commercial basis to learn how to germinate the seeds using GA, But these are all cases of expensive plants with seeds that refuse to normally germinate easy.

The acer palmatum is one where it is usually propagated from cuttings but people would like to get the seeds to germinate more uniformly. Some of these trees can be very valuable. Very beautiful. Japanese Red Maple with thin long leaves.

of course when grown from seed every plant is different. But being able to germinate many seeds would give more variety to look for exceptional plants which can then later be propagated by cloning of some kind.

Here is a link that might be useful:

Another link

Here is a link that might be useful: Hudson