Since 1.14-pre4 there are 2 new weird debug-entries in the debug screen:

After a bit of investigation i found out what these values represent:

They describe the Y coordinate of highest block that exists at your current X/Z coordinates.

It looks like these someone has forgotten to remove these entries, cause no normal player normally uses these values in any way.

In my opinion these values just mess up the debug screen and confuse people so better remove them .