Bleach

I spattered a favourite comfy pair of black trousers with bleach last year. I was reluctant to part with them. I touch them up with black marker. When it fades in the wash I redo it. My grandkids think it’s hilarious.

I don’t know of any way to properly fix the problem.

Could you buy a small decorative item to stitch over it? I have tried the marker pen trick but it usually washes out or colour changes. Depends on the fabric I suspect.

You might get away with permanent black marker pen.
Isn’t it just typical though?
Like tomato sauce when you are wearing a white top.
The Law of Sod

I’ve used permanent black marker ink before and it works well. I pressed over the mark using a cloth and hot iron which helped it to stay black longer.

Oh that’s so frustrating, did it myself years ago when I was cleaning my sink, a permanent marker might help but you will have to keep on doing it,

Yes, permanent black marker works well and on scuffed shoes.

Depending on the fabric, I reckon that permanent market pen would work, even though as Grannynannywanny says, it sounds hilarious. I've done that for tiny spots on my husband's new black T shirt caused by a splash of pool chemicals!

Again, according to what style, fabric etc., you could add some decoration to it, embroidery, a flower, something sparkly, or maybe some fabric paint (perhaps a marker pen would have the same effect). If you have to keep re-doing it, well doesn't matter really - better than not being able to wear it.

As others have said I don't think there's any solution. That's why I won't have have Domestos in the house.
OTOH I once tried diluted hydrogen peroxide - used to bleach hair - to remove fishy/oily smells from boil in the bag kippers from some denims and it worked.
I don't know enough about chemistry to know if it's similar to Domestos.

You could get a dylon pen, £1.99 ebay. The colour does not fade and you only have to do it once.

Fennel Domestos is a hydrogen chloride bleach, not the same as hydrogen peroxide, the laundry/hair bleach. The chloride one is fiercer.

Sorry to say that the brand Domestos was first produced in 1929 by Wilfrid Augustine Handley (1901–1975) [4] , a dentist from Heaton, Newcastle upon Tyne in the North East of England, Which is just over the river from me.

I did that after accidentally buying a spray cleaner that had bleach in it. There was a bleached part on a navy blue favourite cardigan. I used a Sharpie permanent marker to cover it. It does fade over washing but it’s easy enough to re-do it.

Thankyou all so much. I think it will have to be a permanent marker, or a dylon pen.
This top was expensive, but it's not the cost so much,but the fact it's a favourite and I wear it alot.