My Trust Wallet has been hacked/breached - seeking advice

Here's a puzzle for you all:

Today a substantial amount of ETH and an ERC-20 token I had been trading on Uniswap left my wallet to an address I have never seen before. I use an iPhone and my Trust Wallet passphrase is stored in the notes of my iPhone (in retrospect, a very poor decision). Given this my phone must have some kind of virus, correct?

Well here I am trying to learn how to scan my iPhone for viruses only to find out I can't due to it being iOS. Furthermore it is fully updated a of last week.

So friends, how in the sweet living F was my wallet compromised? I have never given my pass phrase to anyone, I don't think I've even opened it in my notes since I put it there. My wallet is on an iOS and so is supposedly insusceptible to malware. I don't click on weird links or watch porn for that matter (on my phone). How is this possible?

Take EVERY precaution you can to protect your funds. To further beat a dead horse, this can in fact happen to anyone. Any advice on how to best protect my crypto in the future would be appreciated. Thanks for reading.

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