it just replaces removed bedrock from both the overworld and nether from the floor/roof of the respected dimensions.
this will NOT be tested in different versions because i just needed one for my server version and so i made it, and made it open to everyone. just know i wont do anything beyond this. if you want more, make your own, you can use my source code to help with that.
it now replaces all bedrock broken, but if you go into creative and break the bottom layer of bedrock you'll see that it is gone and gone forever, but break a random block around you and you'll see it gets replaced. this works cause it is required to break a block after a glitch is used to remove bedrock, meaning it is not possible to get below or above the world.