If my phone were stolen or hacked, and the fact I don't want Google to have any of my bank info.
Many Google apps are untrustworthy and I sometimes install apps that I wouldn't trust with finance information.
I would never type any credit card details into my phone, I don't even trust many if any mobile phone manufacturer.
They would have to be already within the website or app if I was buying something, e.g. Amazon.
Everything you type on your Google Keyboard is logged whether you know it or not, it's how the prediction works.
I have one computer that can access my bank and important emails, that's it.