When create a new world or loading a created world using the server the console show a message when chunks are saved this message use the old names of dimensions for nether and the_end, not sure if this is intended based in how before that message the server show another based in the dimension key and the ThreadedAnvilChunkStorage notice using the legacy names are based in a parameter
Steps
Start the server
Wait for world save
Expected result
When the server notice about save chunks show the current names of levels based in the last update to world storage
Actual result
The server use the legacy names like DIM1 or DIM-1
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