Proton Mail provided Swiss authorities with payment data for defendtheatlantaforest@protonmail.com — the account linked to Stop Cop City protests in Atlanta. The FBI obtained this information through a Mutual Legal Assistance Treaty request on January 25, 2024, identifying the activist behind the anonymous account through their credit card identifier.
Let this be a good reminder that the country that hosts your email service and the treaties/agreements they have are extremely important. A privacy-focused service means little if bad actors can obtain your data anyway via snooping treaties.
How you pay for services like this also matters quite a lot.