It’s a complicated question. To answer it accurately would require a single database of all scientific publications in the world. But so far, our world is not that small. Each of the citation indices covers only a part of the published works. In addition to global ones, there are many national systems for recording and indexing publications.
Moreover, not all authors who use the data correctly cite them. Which, of course, is unfortunate. It is important to cite not only the name of the source, but also its identifier. For example:
GBIF.org (13 September 2022) GBIF Occurrence Download https://doi.org/10.15468/dl.fqur4p
This link doesn’t directly reference iNatutalist, but if click DOI, among the linked datasets is doi.org/10.15468/ab3s5x - iNaturalist Research-grade Observations.
But someone may not use a dataset in GBIF in their publications, but data obtained directly from iNatutalist, or single observations. Since in this case, there is no identifier or clear citation rules, it is difficult to calculate the number of such uses.
Even the “actual” list of publications citing the iNatutalist dataset in GBIF is the result of semi-automated processing of only 6 publication indices. So, the correct answer to your question I would formulate as follows: “there are currently at least 2,202 peer-reviewed publications, including at least 2,157 journal articles, using the iNatutalist Research-grade data.” But these numbers are not exact.