Google Play Security updates can only update a few things on your device. Also, they are available only on devices that have been released tha last 4 years. Only Android 11,12,13 are getting monthly security patches, but then, the vendors must build a new version for your device. Most of vendors are upgrading for 2-3 years their devices and then they stop getting security updates. With a small serch on exploitdb you can see how safe is to still using Android Kitkat in 2023.