The bug

A world / dimension file with min_y -2048 and height 4080 shows this error message but if a world is still generated after this error message occurs the dimension(with the reported "issue") still generates (with min_y 2048 and height 4080). The underside of the bedrock is lighted incorrectly(due to https://bugs.mojang.com/browse/MC-212347?focusedCommentId=911611 ).

The dimension isn't made invalid correctly, or this height setting is actually intended because it is actually cool to have(even though the bedrock is lighted incorrectly) 
This issue relates to MC-212347

How to reproduce

1. Load the custom world file 21w08_MC-218554.json
2. Run the command /execute in minecraft:tallerworld run tp @p 0 -2032 0
   > The flat world generates at -2048
3. (warning: heavy) Run the command /execute in minecraft:tallerworld2 run tp @p 0 -2032 0
   > Normal world terrain still generates till -2048