There's a warning if you try to place a block above the maximum height of the world.

However, this warning doesn't exist at the minimum height of the world.

May be considered a feature request, but with the min and max height now being variable, it would be expected that this message would be shown at the bottom of the world as well, for example for creative players who might not know what the actual limits of the world are (especially in custom dimensions with non-vanilla min and max heights).