Yes, pity and not a long time exposed, I did turn it too. Also I may say my room only got a couple of hours sun in the am before sun moved.
Scotland gets sun but more rain I think! Ah well regret, I don't want to keep quilts folded in a cupboard to keep them good!

Sun fading of dyes/pigments is a fact of life. This is why in museums that have fabrics and embroideries they are protected from the sun/uv light at all times. I also have a copy of a book of house hold hints (by Susannah Watman?) from the 18th C that instructs the servants to close the shutters on the east side of the house in the mornings and the west in the afternoons to preserve the furnishings from the sun.

Sorry to hear that you have been caught out by this, but there is unfortunately no reversal for your fabrics.

Refold and reposition to rotate sun exposure. I don't think there are many fabrics that don't eventually fade in sunlight. I believe it usually happens gradually and overall, but when one side is always toward the sun you'll see a difference. I've used the sun to bleach stubborn stains from white fabic.

Lots of fabrics fade in the sun. Blue is especially notorious. Even carpets will change color with sunlight.

Has other folk found colour fading a fault. I am Self taught quilter from old days before information or tools.
Used dressmaking cotton, cut up clothes, even cotton sheeting,
Polyester wadding, quilting fabric in a corner of shops with
every type of material. No internet, no classes. No quilt shops.
Learned – buy good fabric, do not go cheap, wash fabric!
Never did that when dressmaking - learned quilting every day.
Noticed today a quilt I made and enjoy by draping on my settee back
has fading from light and sunshine on the window side! Fading not
from washing or age . I did not like that lesson I learned! I
I cannot even where I got the fabric Anyone else experiencing
this disappointment?