C# string interpolation-escaping double quotes and curly braces

It seems that you have missed escape for the products and query objects:

$@"{{
    ""name"":""{taskName}"",
    ""products"": [
        {{""product"": ""ndvi_image"", ""actions"": [""mapbox"", ""processed""]}},
        {{""product"": ""true_color"", ""actions"": [""mapbox"", ""processed""]}}
    ],
    ""recurring"":true,
    ""query"": {{
        ""date_from"": ""{dateFromString}"",
        ""date_to"": ""{dateToString}"",
        ""aoi"": {polygon}
    }},
    ""aoi_coverage_percentage"":90
}}";