The bug

Unlike bamboo mosaic blocks, other wooden slabs, and bamboo mosaic stairs, bamboo mosaic slabs are not flammable.

To reproduce

• Execute the following commands and place fire on top of them via flint and steel or fire charge, and wait:

  /fill ~-9 ~ ~-9 ~3 ~ ~3 minecraft:acacia_slab[type=top]
  

• Observe that the slabs burn.

  /fill ~-9 ~ ~-9 ~3 ~ ~3 minecraft:bamboo_mosaic[type=top]
  

• Observe that the blocks burn.

  /fill ~-9 ~ ~-9 ~3 ~ ~3 minecraft:bamboo_mosaic_slab[type=top]
  

Expected result

Bamboo mosaic slabs would burn.

Observed result

Bamboo mosaic slabs don't burn.