In order for the plugin to work you need to do this:
1. Ensure that the server version is not below 1.17.
2. Install the ViaVersion plugin on the server from this link: ViaVersion. Otherwise, the plugin will not start.

Support for RGB colors: {#000000}

This plugin operates as follows: if the plugin is installed on server versions 1.20.1, 1.19, 1.18, and 1.17, and a player joins with a version below these, when the player descends to Y = 0, they won't be able to proceed further. This is because their client version is lower than, for example, 1.17. Essentially, this prevents players from getting stuck in the void, as a bedrock block will be placed under the player's feet. You can adjust this behavior in the config. If a player joins with version 1.17 or higher, there won't be any bedrock under their feet, and the plugin will function normally.

Command: /sncfreload - Used to reload the configuration.
Permission to use the command: sncfreload.reload

From version 1.16.5, I cannot go below Y = 0:
1.16.5.png
From version 1.17.1, I can go below Y = 0:
1.17.1.png