https://m.androidcentral.com/numerous-android-oems-discovered-be-lying-about-security-patches
Wow. I really don’t know what else to say other than wow.
Once a month, Google updates the Android Security Bulletin and releases new monthly patches to fix vulnerabilities and bugs as soon as they pop up. It's no secret that many OEMs are slow to update their hardware with said patches, but it's now been discovered that some of them claim to have updated their phones when, in fact, nothing's changed at all.
Wow. I really don’t know what else to say other than wow.