It seems some-one needs to tell Opera that it is possible to update your app without actually removing it from the store first.
For the 3rd time now their Opera Mini browser app has disappeared from the Windows Phone Store, meaning if you want to download or share it you will get the screen below.
Given the number of times this happened it suggests there is nothing much to worry about, and that it will be back soon, but we have pinged the company to try and get more information.
Keep an eye on the store here for its return.
Update: Opera has acknowledged the issue, and are working on a fix:
@wmpoweruser We are currently working with Windows to fix this issue. Sorry for the inconvenience! /Kendra
— Opera (@opera) July 27, 2015
Thanks Rafael for the tip.