The bug

When /setblock ~ ~ ~ glow_lichen is used without any states specified, it always places the version with all six faces covered. In Java Edition, it places the lichen such that it's attached to every appropriate face, unless there aren't any in which case it places the all-faces version.

How to reproduce

1. Stand on a block with a solid block to your side
2. /setblock ~ ~ ~ glow_lichen

Expected result
Lichen appears below you and attached to the block you're standing next to

Actual result
Lichen appears on all six faces