Metadata has been used in the past to locate people from pictures they took. For an example, see <a href="https://www.npr.org/sections/thetwo-way/2012/12/04/166487197/betrayed-by-metadata-john-mcafee-admits-hes-really-in-guatemala">NPR: Betrayed by metadata, John McAfee admits he's really in Guatemala</a>.
For example, if you log into different accounts on the same website in a single Tails session, the website could determine that the accounts are used by the same person. This is because websites can tell when 2 accounts are using the same Tor circuit.
To prevent an adversary from linking your activities together while using Tails, restart Tails between different activities. For example, restart Tails between checking your work email and your whistleblowing email.
