In addition to this kind of tracking (unless explicitly opt-in with a compliant consent flow without any dark patterns) being in breach of the GDPR, I wonder if

In addition to this kind of tracking (unless explicitly opt-in with a compliant consent flow without any dark patterns) being in breach of the GDPR, I wonder if such mangling of the e-mail address would also be in breach of the right to rectification? Let's assume you willingly opt-in to tracking but for whatever reason want to be tracked under "h.a.n.solo+iab@example.com" and not "hansolo@example.com" (because maybe example.com doesn't strip out + and . characters, so the two addresses are actually separate users), them not allowing you to change it back to your real address (without their normalisation process) might be a breach of the right to rectification as they'd be holding inaccurate personal data about you. Of course this is all completely philosophical as GDPR enforcement is not only severely lacking but is nowhere near technical enough to dig into such detail.