The bug

When viewing glow lichen from a distance, z-fighting is visible.

In the screenshot above, the glow lichen is placed above white concrete. However, this is easy to reproduce with any opaque block. It's also visible with transparent blocks, but it may be more difficult to notice.

Relates to MC-205199.

How to reproduce

1. Fill a large area with an opaque block
2. Fill the block above the opaque blocks with glow lichen
3. Fly away
   Z-fighting occurs between the glow lichen and the block behind it