Datasets
Instead of attaching massive amounts of data as geojson properties, you can use datasets to fetch the necessary data on feature click.
Upload a CSV and then link to them within a layer’s variables with:
"datasetLinks": [{"prop": "{geojson_property_to_match}","dataset": "{dataset_name}","column": "{dataset_column_name}"}]
Note: All matching rows will be returned — not just the first.