The fruit on my kiffir lime tree is orange and abit sweet
It's about 10 years old and the first year it is orange
Certified GKH Gardening Expert
This can happen when it matures for too long on the tree. It is quite possible that they matured faster this year. It sounds like the tree is just old enough for vigorous production. Be sure to pick them when they are still green for the most "limey" taste.
This article will help: https://www.gardeningknowhow.com/edible/fruits/lime/care-of-your-kaffir-lime-tree.htm