Maybe simpler query?

match/tasks.py

@@ -4,7 +4,7 @@
 from celery import group
 from django.conf import settings
 from django.db.utils import IntegrityError
-from django.db.models import Count, Subquery, OuterRef
+from django.db.models import Count, Exists, Subquery, OuterRef
 from django.db.models import Case, When, Sum
 from django.db.models import IntegerField, Q
 from django.utils import timezone
@@ -394,19 +394,18 @@ def celery_task_pool(jobs, pool_size=10):
 @app.task(name="match.tasks.huge_match_import_task")
 def huge_match_import_task(hours_thresh=72, exclude_hours=24, break_early=True):
     thresh = timezone.now() - timedelta(hours=hours_thresh)
-    thresh_epoch_ms = thresh.timestamp() * 1000
-    qs = Participant.objects.filter(
-        match__game_creation__gt=thresh_epoch_ms,
-        match__queue_id__in=[FLEX_QUEUE, SOLO_QUEUE],
-        match__platform_id="NA1",
+
+    qs = Summoner.objects.filter(
+        Exists(Participant.objects.filter(
+            puuid=OuterRef("puuid"),
+            match__queue_id__in=[FLEX_QUEUE, SOLO_QUEUE],
+            match__game_creation_dt__gt=thresh,
+        )),
         puuid__isnull=False,
+        region="na",
+    ).exclude(
+        huge_match_import_at__gt=timezone.now() - timedelta(hours=exclude_hours)
     )
-    qs = qs.exclude(
-        puuid__in=Summoner.objects.filter(
-            huge_match_import_at__gt=timezone.now() - timedelta(hours=exclude_hours),
-        ).values('puuid')
-    )
-    qs = qs.select_related("match").order_by('puuid').distinct('puuid')
 
     count = qs.count()
     logger.info(f"Found {count} participants for huge_match_import_task.")
@@ -418,26 +417,24 @@ def huge_match_import_task(hours_thresh=72, exclude_hours=24, break_early=True):
     elapsed_start = time.perf_counter()
 
     def get_jobs(qs, start_time):
-        for participant in qs:
-            if summoner := Summoner.objects.filter(puuid=participant.puuid).first():
-                if break_early and summoner.huge_match_import_at and summoner.huge_match_import_at > thresh:
-                    # only go back as far as we need to for this summoner
-                    start_time = summoner.huge_match_import_at
+        for summoner in qs:
+            if break_early and summoner.huge_match_import_at and summoner.huge_match_import_at > thresh:
+                # only go back as far as we need to for this summoner
+                start_time = summoner.huge_match_import_at
             if not summoner:
                 continue
             import_time = timezone.now()
             job = import_recent_matches.s(
                 0,
                 10_000,
-                participant.puuid,
-                participant.match.region,
+                summoner.puuid,
+                summoner.region,
                 startTime=start_time,
                 use_celery=False,
             )
             yield job
-            if summoner:
-                summoner.huge_match_import_at = import_time
-                summoner.save(update_fields=["huge_match_import_at"])
+            summoner.huge_match_import_at = import_time
+            summoner.save(update_fields=["huge_match_import_at"])
 
     for _ in celery_task_pool(get_jobs(qs.iterator(2000), thresh), 10):
         i += 1