The software team has removed the One Time Password (OTP) login feature. This step became necessary after a number of issues in the code were detected that might aid malicious users to compromise foreign accounts.
Due to the complexity and some necessary structural changes to fix the problems, the feature will not return anytime soon.
CAcert Arbitration is doing some investigations, including how many users were affected by this change or if there were related issues. All affected users will be notified as soon as possible.