Hi! I think it is because "dit" (your) makes the strawberry definite. Because it is specifically YOUR strawberry. So, the adjective is inflected according to the rule for the definites.
A pink strawberry = et lyserødt jordbær
Pink strawberries = lyserøde jordbær
The pink strawberry = Det lyserøde jordbær
The pink strawberries = De lyserøde jordbær
Your pink strawberry = Dit lyserøde jordbær
His pink strawberry = Hans lyserøde jordbær
Her pink strawberry = Hendes lyserøde jordbær
PS: Can someone clarify if the translation for "pink strawberries" is "lyserøde jordbær"?
Colors are, in every language with which I am acquainted, a matter of personal usage. I would say that pink is simply light red. If you took red paint and added white paint to it, I would call that pink. If you added white paint to green paint, I would call it light green. My wife, though, who has a much larger vocabulary of color words than I, would probably have a completely different word for light green, light blue, light purple, etc. I like my strawberries pink or even a little white toward the stem, but then I like my fruit a bit tart. I would suggest the word you might be looking for is bright red, for the way you like to eat strawberries.
It's like you said. A pink strawberry is underripe, while a light red strawberry is on the cusp of ripeness.
As a gardener, however, I'll note that there are varieties that ripen white to light pink, which usually keeps the birds from eating your crop (unless they're very clever).
In English, we wouldn't normally say "light red", maybe only if you were being very specific about different colors of red (like maybe when you are picking out strawberries!) Lyseroede is the Danish word for the English word "pink". Technically, "pink" is "light red" in English, because it implies red with white added, which makes pink.