This morning my kid asked the voice assistant to "Turn off the computers in this house".
I heard it, thought well that's a strange request but seems harmless because how is home assistant gonna turn off computers.
Me a little while later, "why is shit broken? What's happening!"
Turns out dumb me had adguard exposed to the voice assistant, it switched off all the adguard settings including the DNS rewriting that is the cornerstone of many of my self-hosted services.
I've since revoked that access.
Haha it's a fine balance between preventing this sort of craziness and having a voice assistant that is actually useful because it can do things.
In the settings->voice assistants page you can see exposed entities. Review them and remove anything you don't want it to be able to control.
You can also set up custom commands as an automation. You could probably set up an automation trigger to pick up on the phrases you want to block and respond with "I'm sorry Dave, I'm afraid I can't do that" (or something boring).