Steps to reproduce
Turn off mobgriefing. (Set to false.)
Summon a ghast.
Let it shoot you.
Expected result
You do not get set on fire. (Note that some hits will not set you on fire because they do not damage you at all, but that is a separate bug that can be worked around by changing position slightly between shots: see MCPE-78714. You do get set on fire by damaging hits).
In Java you do not get set on fire by ghast fireballs with mobgriefing off.
The
minecraft:explode
component infireball.json
includes"fire_affected_by_griefing": true,
.
Observed result
You get set on fire by ghast fireballs.
If you set fireballs to be summonable with a behavior pack and summon them on yourself with mobgriefing off then you do not get set on fire. So, I hypothesize that ghast attacks are hard-coded to set mobs on fire and that that is not affected by mobgriefing.
This has nothing to do with mob griefing. Disabling mob griefing can prevent fire ball from creating fire (block). This bug can still be reproduced with mob griefing enabled when a player stands on the block that can't be on fire, like glass.