Mobs will not path off the top of damaging blocks in many cases. They appear to view the 8 blocks surrounding a cactus, magma block, or campfire as damaging, and therefore will not path to them if they have

"avoid_damage_blocks": true

within "minecraft:navigation.walk". That means they will not leave the top of a damage block if it is elevated, unless they target something farther away than 1 block. For example, if you spawn a wolf on a cactus, magma block, or campfire, and a sheep next to the block, the wolf will get angry but will not move until the sheep begins to wander away. Moreover, the panic behavior seems to be restricted to targeting adjacent blocks, so mobs with "minecraft:behavior.panic" (e.g. llamas, chickens) will not step down from a cactus as they should because they can’t find a “safe” block.

Steps to reproduce

1. Place a cactus block on sand.
2. Summon a mob on top of the cactus.

Expected result

The mob moves off of the cactus because it is getting hurt!

Actual result

Most mobs will not path off of the cactus.