Leaflet polygon with multiple geometries

Question

I'm trying to make a weather radar that displays alert polygons from the NWS API. For some of these alerts, the geometry is stored in separate links:

{
            "id": "https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.235b453f6211d665365a573e200008d44979bdce.001.1",
            "type": "Feature",
            "geometry": null,
            "properties": {
                "@id": "https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.235b453f6211d665365a573e200008d44979bdce.001.1",
                "@type": "wx:Alert",
                "id": "urn:oid:2.49.0.1.840.0.235b453f6211d665365a573e200008d44979bdce.001.1",
                "areaDesc": "Todd; Morrison; Mille Lacs; Kanabec; Benton; Isanti; Chisago; Polk; Barron; Rusk",
                "geocode": {
                    "SAME": [
                        ...
                    ],
                    "UGC": [
                        ...
                    ]
                },
                "affectedZones": [
                    "https://api.weather.gov/zones/forecast/MNZ042",
                    "https://api.weather.gov/zones/forecast/MNZ043",
                    "https://api.weather.gov/zones/forecast/MNZ044",
                    "https://api.weather.gov/zones/forecast/MNZ045",
                    "https://api.weather.gov/zones/forecast/MNZ050",
                    "https://api.weather.gov/zones/forecast/MNZ052",
                    "https://api.weather.gov/zones/forecast/MNZ053",
                    "https://api.weather.gov/zones/forecast/WIZ014",
                    "https://api.weather.gov/zones/forecast/WIZ015",
                    "https://api.weather.gov/zones/forecast/WIZ016"
                ],

and every link has geometry in it:

{
    "@context": {
        "@version": "1.1"
    },
    "id": "https://api.weather.gov/zones/forecast/MNZ042",
    "type": "Feature",
    "geometry": {
        "type": "Polygon",
        "coordinates": [
            [
                [
                    -94.732093800000001,
                    46.369010899999999
                ],
                [
                    -94.731994600000007,
                    46.366912800000001
                ],
                [
                    -94.731094300000009,
                    46.363113400000003
                ],
                ...

I tried to do this:

if (alert.geometry) {
                    geometry = alert.geometry;
                } else {
                    const affectedZoneGeometries = await Promise.all(
                        alert.properties.affectedZones.map(async (zone) => {
                            const res = await fetch(zone);
                            const zoneData = await res.json();
                            return zoneData.geometry.coordinates;
                        })
                    );

                    geometry = {
                        'coordinates': affectedZoneGeometries,
                        'type': 'MultiPolygon'
                    }
                }

Which is logged as:

but the polygons will not display on the map. I suspect that this is due to incorrect polygon parsing, but I don't know the solution to it.