When you login from an unknown device Moodle sends a mail to inform you, just in case your account was hijacked.

The mail contains your account name, mail address, date and time, user agent, IP address and a footnote that should contain the URL how to change the password (note: I have a custom change password link set up for LDAP accounts).

But the variable is not replaced in the template, the mails contains literally:

Links:

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[1] /{$a->changepasswordlink}