As an InfoSec professional, what you describe sounds more like a device-level compromise of your iphone, perhaps through a malicious app, or link you clicked.
What your experienced can't be done with just a sim swap attack, as you would have lost access to your phone number. And it can't be done with the described T-Mobile hack, as it would have given the hackers silent access to your texts, so they could have reset your Gmail password, but then you would have noticed a password change (and you claim it didn't change.)
What your experienced can't be done with just a sim swap attack, as you would have lost access to your phone number. And it can't be done with the described T-Mobile hack, as it would have given the hackers silent access to your texts, so they could have reset your Gmail password, but then you would have noticed a password change (and you claim it didn't change.)