We generally only fully support the latest version, the same applies to exploits such as server crashes and item duplication bugs. In the transition period during larger Minecraft updates, we may still backport important fixes to the last minor or major release.
For any issues that are NOT duplication bugs, server/client crashes, or otherwise serious exploits, please open an issue through the Issues tab. For exploits, please join our Discord and see the #paper-exploit-report channel for further instructions.