we have indeed indexed iNaturalist since then. The query you have issued is looking for an exact date though. To find all records since that date you need to use a range query like this:
This is documented here and should be linked from the search parameter descriptions if they support range queries:
If you want to filter records for a single dataset using the datasetKey might be safer to avoid records from other datasets accidently using the same codes:
best,
Markus
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Markus Döring
Software Developer
Global Biodiversity Information Facility (GBIF)