Could be that Travelex is trying to get rid of 2000 yen notes.
Most vending machines in Japan still do accept 2000 yen notes. If a machine does not accept 2000 yen notes, then there is a sign but it is in Japanese posted such as 「2千円札は使えません。」. One specific example I know is fare/ticket machines for Sapporo subway do not accept 2000 yen notes.