Given the amount of factors that go into ad targeting it's pretty much impossible to prove without a source code audit. It also means it's easy for Google to do

Given the amount of factors that go into ad targeting it's pretty much impossible to prove without a source code audit. It also means it's easy for Google to do it and get away with it as nobody can prove it. Given the business model of Google, I wouldn't be surprised if they did it, especially considering they've already proven their bad faith with various dark patterns and their intentional refusal to comply with the GDPR (for 4 years their "consent" flow wasn't compliant as you couldn't decline as easily as accept).