There should be a config value to disable safety teleport & automatically placing dirt blocks, as this is essentially griefing the original build by placing an unnecessary dirt block (This can be an issue on adventure mode worlds)

I'd +1 this, or at least improve the mechanism that the safety teleport uses to place the block. ATM it can delete blocks like player heads if someone teleports to one suspended in the air. This caused a bit of a headache on my server and required a /co restore to fix - ideally the dirt block should disappear back to whatever it used to be when the person teleporting moves, or maybe just deny the teleport unless the person's flying per config (?)

This has been resolved here: 66b77ee

The following changes have been made:

1. A safety block is only placed if the player is in Survival mode.
2. Safety blocks will no longer replace other solid blocks such as player heads.
3. The safety block will now use an invisible barrier instead of dirt, on Spigot/Paper servers.
4. The safety block will automatically be removed/reverted after 60 seconds, or on server shutdown.