Detergent fragrance tasting bread

While I agree with the other answer that it's flavoured with something you don't expect, the other possibility is that the bread was wrapped in a freshly laundered, strongly scented cloth. You may be particularly sensitive given that they prefer unscented products. That would affect the crust much more than the inside.

One time I was making a focaccia and instead of spraying a water mist in the oven I accidentally sprayed kitchen cleaner in the very hot oven! This did not go well. I got a face full of super-heated kitchen cleaner and the bread smelled and tasted of chemicals so I had to throw it away.

I doubt very much that this is the case with your friend's bread though. Most likely the taste is from an ingredient in the bread that has a strong flavor. Spices like aniseed, fennel, cardamom, or herbs like lavender are very aromatic and add strong flavors as well which some would say are very chemical-like. Some people like this, some people do not and it's fair to say you are one of the latter. Those ingredients are safe to eat, just not to your taste.

A test of whether it is an ingredient or an actual cleaning product causing the smell and taste would be to pull a bit of the bread from the center and taste it in isolation. Take your sample to a different room away from the other bread to test it. If your sample tastes like detergent it's in the ingredients, if the smell and taste is only on the outside of the bread or close to the surface then it's likely actual chemicals.

A plausible reason is the oven being cleaned with a product not intended for that purpose. I once had somebody help me clean and using an all-purpose cleaner on the oven, and after that, for about 10 baking sessions, i could smell the fragrance during baking. I suspect that the smell may have stuck to the food too, although i didn't notice it after spending hours in the kitchen that was permeated by the same smell.

Another possibility is the bread being wrapped in a freshly washed towel right after baking.

The third, some cheaper cosmetics are perfumed with the same aldehydes used in detergents (chemically, you cannot make smells last without this kind of base, and the few ones that are cheap and safe are reused on different product families). If somebody kneaded the bread by hand after using hand cream, some traces can have gone in. I doubt that many people will notice such small amounts given how well it noises are adapted to these events, but you said you're not using them in your household, so you'll detect it easier.

No matter how it came there, if it is indeed detergent, it is not going to hurt you. Household products are intentionally formulated such that even a child chugging down a bottle doesn't get poisoned. Any adverse effects should be minimal, if they happen at all. Of course, this isn't an invitation to eat detergent on purpose, but if the bread had some traces of it, there isn't any reason to panic.

I think often people knead dough by hand, without ensuring their hands have no fragrance on them from hand soap. My tip is to give hands a good scrub, rinse, and a rigorous dry on a towel to rub any remaining fragrance off before kneading dough. Also, bread covered for hours by a tea towel washed with a strongly scented detergent might taint things too

I find this issue in A LOT of breads or cookies given to me from other people, EVEN if they're not homemade! I don't know if I just have a very good-sensing palate or what, but others don't seem to mind eating the same thing that smells like some kind of fragrance (most usually smell like the fragrant inside of that person's house). I cannot. I agree that it is ruined for me. Anyway, all that to say I believe it to be that the bread has simply absorbed the smells of the environment it was in. Especially if that environment has a particularly strong smell.

I remember receiving a lunch from someone whose house smelled really good -- they used either wall plug-ins, sachets, or some kind of potpourri-type thing for rooms. The sliced bread (from the grocery store) smelled like her house. This has happened very often with different people and bread items, but I can detect it right away and can't finish it -- no matter how tasty it would have been. ?

Possibly contaminated

I live on an island where all wheat flour is imported by cargo ship containers and fumigated as it enters the country.

This makes all flour, crackers, and similar items that are packaged in somewhat gas permeable packages taste perfume-like.

If the bread was imported, or the flour used to bake the bread was imported, then it could have absorbed some of the fumigation products.

It’s definitely absorbing scents from the home. My in-laws regularly give us food and baked goods and everything tastes like their laundry/dryer sheets. I can’t eat it. My kids don’t mind. I notice it from other people who give us food too. Baked goods especially but also meat and other dishes. It’s so hard to not just tell them their food tastes bad. Feels like a waste when it goes uneaten.