Either your wallet was hacked or someone had access to your seed phrase.
Whatever happened, bitcoin transactions are irreversible and there's nothing you can do.
But how, I need to insert a password for each time I send?
Itīs not like I have my seed phrase on my sticky notes, itīs not easily accessible, and it looks like this was sent automatically.
It says "self-transfer" when I run a privacy analysis on blockstream.info
Sometimes when you want paste address, another unknown address will replace in your clipboard you should check every time that you want send transactions,and when you see that somehow an unknown transaction sent from your wallet you can double spend to cancel that transaction before confirm