Since Android eleven is not receiving safety patch backports, the LineageOS crew has determined to sunset LineageOS 18.1 (which is based totally on Android eleven).
Manually backporting safety patches may be difficult to do, and there is even a danger that in writing a new patch, they could introduce new vulnerabilities.
Unfortunately, some gadgets with LineageOS 18.1 builds available do not have an improved path to more recent releases. This is because Android 12 made it a requirement to help in-kernel eBPF, a function that isn’t supported (formally or through backports) on Linux kernel variations 3.18 and older.
Check out LineageOS 21 if it’s available on your tool, although. There are lots of cool new functions!