If you use external signers like Amber you could just revoke the permission to change your relay list.
I am using Amber, but apparently I'm not yet that advanced. I didn't even think of this possibility, so thanks for ppinting it out to me.
What kind of event would that be? Is there a list where I can see the corresponding action to the NIPs or event numbers?
The kind number for your relay list is 10002. Delete it if you don't want an app to change it. You can look up all the different event kinds here: https://github.com/nostr-protocol/nips?tab=readme-ov-file#event-kinds