The search giant announced earlier this week that it had killed off its Federated Learning of Cohorts in favour of Topics, a new proposal under which web browsers will be able to retain three weeks' worth of browsing data.
One marketing executive told the BBC: "This constant indecision does not inspire confidence."
Explaining the latest move, Farhad Divecha, founder of digital marketing agency AccuraCast told the BBC that it “didn’t make sense to most advertisers, who aren’t technical data analysts”.
“The system was met with a lot of criticism when Google launched it,” he explained, “and it largely felt like a half-baked idea Google prematurely pushed out the door in response to changes in advertising and privacy.”
“The past year has made it fairly clear that Google still aren’t really sure of the best way forward.”
Google’s new Topics proposal works by grouping web users in topic clusters, of which there are about 350 categories such as health and travel.
Topics identifies users’ interests and then stores them for up to three weeks before deleting them.
When a user visits a website, Topics will then show the site and its advertising partners three of the user’s interests from the last three weeks but without sharing any sensitive data such as race or gender.
Users would also be able to disable the feature entirely.
Trade Desk UK vice-president Phil Duffield questioned the system telling the BBC: "Google's latest proposal on Topics is limited to one channel - its Chrome browser - and can't be applied to the multiple devices the majority of consumers use to access the open internet. This means that advertisers are restricted to basic targeting approaches."
Bennet Cyphers, from Electronic Frontiers Foundation, told The Verge that whilst better than Floc, Topics would “still tell third-party trackers what kind of sites you browse.”
Likewise, Peter Snyder, company director of privacy-focused web browser Brave, said: “The Topics API is, at root, the same idea as Floc.”
He points out that in “both proposals, the browser watches the sites you visit, uses that information to categorise your browsing interest, and then has the browser share that info back with advertisers.”
He believes it should not be up to Google to be “the arbiter of what users consider ‘sensitive’ data.”
“People should decide what they consider sensitive - not Google,” Mr Snyder said.
He added that Google were “paying lip service to protecting the open web” whilst maintaining market dominance.
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