Just got hacked I think…can anyone help me understand how?

Looking for some help. Im pretty new to crypto and recently setup a wallet and started buying a few different things.

This morning I was checking my MetaMask wallet and 774 of OPTI was sent, but not by me….

How could this happen and how to avoid in the future?

Glad it was only $300 and not $300,000

Heres the wallet it was sent to :

0x3895c7e8c65c4ad1102e16689a9f83b56bc67c14

Any ideas?