If you use Chrome, Google can use a network protocol for tracking and ad delivery that can't be seen or blocked by extensions. TL;DR: You really shouldn't use a web browser made by an ad company.

"AdBlock Plus, uBlock Origin, and other extensions cannot block QUIC requests. Recommended best practice is to disable QUIC from the chrome://flags/ URL."

https://blog.brave.com/quic-in-the-wild-for-google-ad-advantage/

@ocdtrekkie QUIC has an IETF workgroup associated with it https://datatracker.ietf.org/wg/quic/documents/ It's implemented in Opera as well and will likely proliferate through the other browsers soon. Hostfile based blocking should still work in the meantime.

@Irick The biggest issue is whether or not it can be monitored like other traffic.

I usually trust things like Privacy Badger to be able to conclusively tell me if there's tracking software embedded in a website I visit.

@ocdtrekkie It's not a bad idea assumption, but I'd argue that the extensions should probably start to support it. It looks like enough people think it's useful that it's going to get accepted into the IETF standards group.
@Irick The article suggests that Chrome's API currently limits the ability for said extensions to detect it.
@ocdtrekkie Yeah, looks like it's limited to chrome://net-internals/ for viewing sessions ATM. That will have to change though, if they want to keep their developer mindshare on chrome. That interface is utter crap for troubleshooting.