Does Erase All Content and Settings log me out of my Gmail on safari?

Hello, I recently traded in my old iPhone 8 Plus at At&t and did the Erase All Content and Settings action, and I think that wiped everything off on the phone that was related to me (I double-checked and set up the phone without an apple account and looked around to be sure). However I checked my Gmail account and somehow it says I was still online on my Gmail account in that iPhone 8 Plus through Safari, and I quickly logged out my Gmail account in it through my computer. But shouldnt Safari have also lost all its data from the Erase All Content and Settings option?