Paper1.21: The server core cannot brush blankets, rails, and TNT

[二次元的香瓜]

Paper1.21： 服务器核心无法刷毯子、导轨和 TNT

 

[EterNity]

You need to re-enable it in the config file.
你需要在配置文件中重新允许它

unsupported-settings: allow-piston-duplication: true
https://docs.papermc.io/paper/misc/paper-bug-fixes