EMBED PDF API : fail after 190 annotations load

Hello,
I am using the EMBED PDF API to dynamically load annotations created by the same API. Everything works fine up to a certain point, around 190 annotations. After that, an error message appears indicating a failure, but without any detailed log.
I tried loading page by page, without success (it doesn’t seem to be an RPM issue).
Should I consider switching to a paid plan?
Thank you for your help.