I wanted to chime in on this topic @mariatogonon so that the team was aware this wasn’t a one-off issue. I encountered the same problem as @edluvables. Same setup, fresh install across the board, everything up-to-date. Immediately after adding a gravity form to my homepage, I received the 403 Forbidden Plesk page. Found the same errors within the server logs. Whitelisting the IDs mentioned resolved my issue right away. I’ve used gravity forms on a ton of different projects with very similar setups and I’ve never had an issue using it with Plesk. This seems like a bug that needs to be addressed.
Thanks again @edluvables for the guidance!