Barrier and light blocks at the beginning of a section in a chunk (2 blocks high) dark when RTX graphics are enabled

Summary:
With RTX graphics enabled, the barrier blocks or lights block at the very bottom of sections in a chunk will darken (darker compared to other barrier blocks and lights block ).

Steps to reproduce:

1. Turn on RTX.
2. Build a pillar of barriers or a light block 16 blocks high.

Observed results:
2 blocks of barrier or light block will darken.

Expected results:
Barriers and light blocks should not darken at the beginning of a section in a chunk.

Screenshots: