Since I have been using some unsigned device drivers and programs recently, I decided to do a clean re-install of Windows 10. I have an Ubuntu installation in the same laptop. So I used a USB stick prepared by Windows to boot from, formatted the windows installation partition and reinstalled Windows. I left the ESP and Recovery partitions untouched.
After logging in to the new installation, I noticed that Microsoft Edge still has the autocomplete data, like e-mails that was used in previous installation. I never typed any e-mail addresses in the new installation, but when I try to login to my Microsoft account, the other e-mail address pop up in suggestions.
My concern is, what else could persist across a format-reinstall like this? Does this beat the purpose of a clean re-install? Are these data coming from the Recovery partition ? (about 508MB, created during original install?) Is it possible that a malicious/untrusted program could also have survived the same way ?