shinyapps.io user:- file upload limit

I have a shinyapp which is used to process files from tree sampling equipment and extract wood quality information.

https://forestquality.shinyapps.io/FWPA-4/

Until recently it seemed to handle uploads of 1500+ individual files OK (each file being around 10-40K).

Recently I and my users have been getting an error when loading more than 500 files. The upload works OK on my local machine; the issue only becomes apparent when uploaded to shinyapps.io

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