Sony made it very clear that the PS Vita was dead to them this year by ending production back in March. But oddly, they're still updating it. Usually, when a company is done with a product, they cease all operations. Not just in building them, but also with updates. However, that's not the case with Sony. Not only are they sending firmware updates to the portable console, but this is the fourth one in 2019.
An update to the system software for PlayStation Vita systems and PlayStation TV systems was released on October 16th, 2019. You can use this to update your system software to version 3.73. Always update your system to the latest version of the system software. By updating, you can enjoy additional features, improved usability, and enhanced security. The PlayStation TV system is sold as PlayStation Vita TV system in some countries and regions. Systems with either name are referred to as "PlayStation TV" or "PS TV" on this page.
We're guessing the updates are being sent for those players who still own a PS Vita and use it with their PS4 still. But we're guessing these updates will come to an end soon when the PS5 launches.