hi, i been going around the internet trying to find the same answers to your problem, it has been a while ago today and i am tired but ill try to answer as best i could and how i understand it, subframes are sub processes that are used to isolate the things running on websites and web apps, etc, to protect your browser and to make the browser more effiecent, when a subframe is deleted it looks like it stops the ads running on that page, even though subframes are said to be common, normal and safe, it doesnt look like that to be true, others say subframes are most common to be used to run in browser bitcoin miners, or other invasion habits, especially when they take over the ram, cpu, hard drive, deleting them is not enough as they come back,
the question is how did they get ahold of the browser? this does not happen on its own, so then the question is, what did we allow to get in? have a place in our browser? first is extensions, so delete all extensions, but that didnt work, so next delete all the 3rd party apps in the apps tab, that helped a lot but some still popped up, what else? maybe you a custom theme, chrome has their own but they allow others to share their custom browser themes, i deleted that and went with one from google.
that should clean your browser up but next i found "clean my computer" in settings, privacy and security
then i updated my browser, which was having a hard time to do, for some reason i was kept from doing that, so i downloaded chrome from google, run and it was a seamless update with no loss of personal bookmarks and accounts. and now chrome is running fine although a little slow but zero subframes so far,
there is a chrome page
chrome://flags
that has browser improving and tweak security, look up secur and it should bring up one called strict-origin-isolation and i hear this will improve security, i think this is what subframes were, and perhaps subframes were isolation those sites, but i dont know for sure. anyways hope this helps you
they also said that it could be that your account is corrupted, targeted so you may have to make a new account and import all your stuff, but somewhere in your old stuff is what got you targeted. i hope someone has more information that I got
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