When glow lichen is placed in lava source blocks, a waterlogged glow lichen is placed, thus a water source block is created. Other waterloggable blocks don't have this issue.
I expect glow lichen either to be lavalogged (but that's strange) or to remove the lava without creating water when placing it in a lava source block.
If placed in a lava source block, the lava the lichen is placed in converts to a water source block and the glow lichen is placed as a waterlogged block into the created water block. Any surrounding lava reacts with the new water accordingly. Placing lichen in flowing lava works properly, but flowing fluids don't seem to destroy the lichen (reported in
- Find or create a pool of lava (source blocks)
- Place glow lichen in one of the lava source blocks
The lava converts to water