Status effects are actually deleted/handled when the mob is deleted

code/datums/status_effects/status_effect.dm

@@ -8,6 +8,7 @@
 	var/tick_interval = 10 //How many deciseconds between ticks, approximately. Leave at 10 for every second.
 	var/mob/living/owner //The mob affected by the status effect.
 	var/status_type = STATUS_EFFECT_UNIQUE //How many of the effect can be on one mob, and what happens when you try to add another
+	var/on_remove_on_mob_delete = FALSE //if we call on_remove() when the mob is deleted
 	var/alert_type = /obj/screen/alert/status_effect //the alert thrown by the status effect, contains name and description
 
 /datum/status_effect/New(mob/living/new_owner)
@@ -21,8 +22,9 @@
 	STOP_PROCESSING(SSfastprocess, src)
 	if(owner)
 		owner.clear_alert(id)
-		on_remove()
 		LAZYREMOVE(owner.status_effects, src)
+		on_remove()
+		owner = null
 	return ..()
 
 /datum/status_effect/proc/start_ticking()
@@ -52,8 +54,8 @@
 
 /datum/status_effect/proc/on_apply() //Called whenever the buff is applied.
 /datum/status_effect/proc/tick() //Called every tick.
-/datum/status_effect/proc/on_remove() //Called whenever the buff expires or is removed.
-/datum/status_effect/proc/be_replaced() //Called instead of on_remove when a status effect is replaced by itself
+/datum/status_effect/proc/on_remove() //Called whenever the buff expires or is removed; do note that at the point this is called, it is out of the owner's status_effects but owner is not yet null
+/datum/status_effect/proc/be_replaced() //Called instead of on_remove when a status effect is replaced by itself or when a status effect with on_remove_on_mob_delete = FALSE has its mob deleted
 	owner.clear_alert(id)
 	LAZYREMOVE(owner.status_effects, src)
 	owner = null

code/modules/mob/living/living.dm

@@ -29,6 +29,13 @@
 	med_hud_set_status()
 
 /mob/living/Destroy()
+	if(LAZYLEN(status_effects))
+		for(var/s in status_effects)
+			var/datum/status_effect/S = s
+			if(S.on_remove_on_mob_delete) //the status effect calls on_remove when its mob is deleted
+				qdel(S)
+			else
+				S.be_replaced()
 	if(ranged_ability)
 		ranged_ability.remove_ranged_ability(src)
 	if(buckled)