How did my late father's Google account appear on my iPhone?

My name is Claudia. My father, who was also my best friend, passed away on 2nd July 2026. My heart is irreparably broken.

I'm posting this because I'm trying to understand something that happened on my iPhone, and I'm hoping someone can offer a technical explanation.

A few days after my dad passed, I downloaded an AI app because I wanted to hear all the notes I had written as a song in memory of him. When I selected "Sign in with Google", I expected to see my own Google account, as I always have, because it's the only Google account I have ever used on my iPhone.

Instead, the ONLY account that appeared as an option was my dad's Google account. My own account didn't appear at all.

This completely shocked me because my dad had never used my phone, I had never signed into any of his accounts, and I didn't even know he had an email address (especially a gmail) until that moment. 

He had an old Android phone, rarely used it, could barely text, had no social media, and mainly used WhatsApp. He hadn't worked for decades, and the only time I ever remember him sending an email was around twenty years ago when my mum wrote it for him. Even then, I believe it was probably sent from my mum's email address.

I didn't sign into his account through the AI app because I was so confused and didn't want to be disrespectful.

Then, a couple of days later, I was using Safari on my iPhone and searching Google Images for "Anxiety from Inside Out" because I was mocking my sister saying that's who she looked like and I wanted to show my other siblings what I was referring to. 

My phone glitched on safari whilst I was scrolling the images, and a Google account pop-up selection/sign-in screen suddenly appeared. It was my dad's Google account again. 

This time, I thought, what have I got to lose?
I clicked the account, and I was signed in immediately without being asked for a password, two-factor authentication, Face ID, or any other verification.
I then spent the rest of the evening alone, looking through his Google search history for comfort. He had rarely used Google, but the few searches he had made were so sweet that they reduced me to tears.

The following day, I spoke to my mum and asked whether Dad had a Gmail/Google account. She said that he did and told me the email address. It matched exactly the account that had appeared on my iPhone.

So I later confirmed that it genuinely was my dad’s Google account, the same one he had been signed into on his own Android phone. However, that account had never been signed into on my iPhone, and my dad had never used my phone.

To summarise, and all I can confirm with complete honesty:
• I have never signed into his Google account before.
• I have never entered his email address or password on my phone.
• My dad had never used my iPhone, ever.
• His phone was an Android, not an iPhone.
• I didn't even know his email address existed until the first incident with the AI app.

I have deliberately remained signed into his account because I'm worried that if I sign out, I may never be able to access it again. Although I remain signed into his account in Safari, I have since signed back into the Google app using my own Google account. So both accounts are now currently active on my phone as I don't want to lose any evidential "logs" from my father's account that could help me understand how this happened.

In essence, it would be the equivalent of a random stranger's account linking to my phone - that's how unlikely it is. If my mum's Google account had appeared, I might have assumed I'd accidentally signed into it at some point because I know her Gmail address by heart. Even then it would have been unusual. But my dad's account appearing was something I genuinely could say would be impossible, especially when he had passed the week before.

Has anyone ever experienced anything like this, or can anyone explain how my dad's Google account could have appeared as the only Google account on my iPhone, when my own account didn't appear, and then later allowed me to sign in without entering any credentials?

Is there any legitimate technical explanation for this? 
Could his account somehow have become associated with my iPhone without either of us knowingly signing into it?

I'm genuinely trying to understand how this is technically possible and would be incredibly grateful for any explanations.

Thank you so much in advance.