Falling block entity below Y 1 drops as item after 100 ticks

The bug

Falling block entities which are below Y 1 drop already after 100 ticks instead of the default 600.

Expected behavior

Falling block entities should drop as item after 100 ticks if they are below Y 0 because Y 1 can still be considered "in the world".

How to reproduce

Summon a falling block entity below Y 1 but above or at Y 0 with a Time value of 100

/summon falling_block ~ 0 ~ {Time:100,NoGravity:1b}

→ You will see that the falling block instantly drops as item