“As part of the UID2 API they specifically describe how an advertiser must "normalise" their users’ email addresses.”
UID2 ties your email address to everything you sign into, from websites to TV apps. Users fight back with dotted Gmail addresses and plus tags, so they can see who sold them out. The IAB’s spec strips both, turning [email protected] back into [email protected]. Asked to stop, the IAB said it “thought long about this” and won’t. The ad industry’s standard is built to defeat the one trick users have for catching it.