@Marek Zlatník Thanks for reaching out and sincere apologies for the delay on this. We are constantly trying to reduce our answer time and in coming days you will see a significant improvement here. So we appreciate you posting your future queries here.
Coming to your question, there is nothing much that we can do during the process of converting the type of the file.
You can try AIP scanner once the PDF has been created and then try to apply the automatic label.
Please do note that the scanner does not discover and label in real time. It systematically crawls through files on data stores that you specify. Configure this cycle to run once, or repeatedly.
You can read more about the AIP scanner here : https://learn.microsoft.com/en-us/azure/information-protection/deploy-aip-scanner
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