Tale of Fairy (Mama Fairy And The Woodcutter)
South Korean fantasy series, 2018, currently broadcasted.
It's about a fairy who was left back on earth and fell in love with a human 700 years ago. Now she appears as an old woman, but her true appearance - a young woman - can be seen by the audience, or while she is naked.
I skipped through the first 10 episodes and apart from the cut-away scenes I didn't spot any age TF sequence. But as there are a few quick animal TF scenes with her daughter-cat, maybe there will be one in the last episode, when she and her love interest have an epic kiss.