I chose my webhook to only push post event because it covers both new topics made and new posts/replies made.
The issue: it alerts everytime someone sends a private message. I know that private messages are technically a topic but shouldn’t there be a way to block that out or at least only deliver topic replies and creations?
Also, anyone can click to view the private message even if theyre not invited to it 
It’s not possible to filter pm replies in post event webhooks. But you can do it via a custom plugin.
If you are not an admin and don’t have access to the PM then you can’t view the messages in it.
that screenshot looks like Discord to me. Have you thought about using the discourse-chat-integration plugin instead of webhooks? It provides loads of filtering options:
