Don't expect that to last long. iOS 14.8 was released on September 13, 2021, iOS 14.8.1 on October 26, 2021, and then nothing else.
iOS 12.5.6 was released 8 days ago for the 5s…
That was a weird one, but nonetheless, here's the list of security update, and there's been nothing for older versions since October 2021. https://support.apple.com/en-us/HT201222
Also note that 12.5.6 was for a single actively exploited CVE and no other vulnerabilities.
Were there devices that supported 14 and not 15? That’s probably why they dropped support, you can just upgrade to 15 and get the security update.