This is one of two mid/near end month promos! The big one is the IHeartSapphfic end of year sale, where all books are marked down to $0.99! Including several of my own.
Smashwords is having a big end of the year sale. This promo is only a small fraction of that, but highlights queer books in particular. For the full list, go here.
This second one is a bit more complicated, but lasts until the middle of January. Kindle Vella is Amazon's serial platform, currently exclusive to Americans or those with American accounts, but that may change early next year.
You buy token bundles and use those to unlock episodes, although new users receive up to 500 free tokens to start. Commenting is currently in beta, but readers can like (thumbs up) episodes and "fave" the stories they like the most (once a week thing). Liking and faving are very important to authors and affect bonuses.
You can read these stories on your phone or tablet, but currently not on a Kindle.
This is a good example of what Vella looks like on mobile devices: