Anti-Exploit plugins resolve issues such as crashes, dupes, abusive NBT etc.
Some of these plugins might only be useful if you are not using the latest version of Paper.
Panilla prevents abusive NBT and packets. Average or lenient modes recommended. Recently was found to be messing with items contained within shulkers, so test the plugin before you install it on production.
Avoids NettyCrashers, slightly prevents Anti-Anti-Xrays, logs packets and limits them.
Improve the security of your Minecraft server by filtering illegal content from player created books. Although personally I would completely disable books because I don’t trust them at all, you may use this plugin instead.