As noted in our project description, Paper fixes gameplay and mechanics inconsistencies.

TNT duping, Carpet and Rail duping, and breaking Bedrock and End Portals, and Gravity Block Duping have been patched in Paper 1.15.2+.

Because TNT duping is considered a form of automated mining and not a resource dupe, we have provided an option to restore it. This undesirably also re-enables carpet and rail duping, which normally we would not provide a config for, but its the same bug for those.

Also, considering bedrock breaking is more of a security thing, an option has been provided for that too.

However, Sand/Gravity block duping does not and will not have a config option.

To restore TNT, Rails and Carpet duping, enable the following config:

settings:
  unsupported-settings:
    allow-piston-duplication: true

To enable bedrock and End portal block destruction, enable the following config:

settings:
  unsupported-settings:
    allow-permanent-block-break-exploits: true

If your server has lag, crashing or any other undesirable consequences from enabling these flags, you will not get support from Paper.

For reasoning behind no config for sand (and MANY other duplication bugs), see: #3724

Please do not open any further discussion on config options for sand duping. The decision is final. It will be closed.

If you wish to have all of the vanilla bugs with better performance, please use Fabric with the Lithium and Phosphor mods instead, or Sponge for your server.