## Bug description

I have lost edit permissions to a [dashboard I created](https://app.posthog.com/dashboard/28987), despite still being listed as the owner of the dashboard

## Expected behavior

I should still be able to edit the dashboard

## How to reproduce

I noticed this problem after adding a new insight, but this doesn't appear to be the cause of the issue. I've duplicated the dashboard to restore access and adding a new insight didn't appear to cause the issue 

## Environment

- [x] PostHog Cloud
- [ ] self-hosted PostHog (ClickHouse-based), version/commit: _please provide_
- [ ] self-hosted PostHog (Postgres-based, legacy), version/commit: _please provide_

## Additional context

#### *Thank you* for your bug report – we love squashing them!

posthog/api/dashboard.py
if self.context["view"].action == "list":
            return None
        items = dashboard.items.filter(deleted=False).order_by("order").all()
        self.context.update({"dashboard": dashboard})
        dive_source_id = self.context["request"].GET.get("dive_source_id")
        if dive_source_id is not None:
            items = self.add_dive_source_item(items, int(dive_source_id))
        
        
        for item in items:
            if not item.filters.get("insight"):
                item.filters["insight"] = INSIGHT_TRENDS
                item.save()
        return InsightSerializer(items, many=True, context=self.context).data
    def get_effective_privilege_level(self, dashboard: Dashboard) -> Dashboard.PrivilegeLevel:
        return dashboard.get_effective_privilege_level(self.context["request"].user)
    def validate(self, data):
        if data.get("use_dashboard", None) and data.get("use_template", None):
            raise serializers.ValidationError("`use_dashboard` and `use_template` cannot be used together")
        return data
    def _update_creation_mode(self, validated_data, use_template: str, use_dashboard: int):
        if use_template:
            return {**validated_data, "creation_mode": "template"}
        if use_dashboard:
            return {**validated_data, "creation_mode": "duplicate"}
        return {**validated_data, "creation_mode": "default"}
class DashboardsViewSet(TaggedItemViewSetMixin, StructuredViewSetMixin, viewsets.ModelViewSet):