If you are using an image HTTPS proxy, an attacker can simply attack your image proxy since the proxy fetches insecure content.Even worse: if your image proxy serves these images from the same domain as your Nextcloud installation you are vulnerable to XSS via SVG images.
Facebook was the first to discontinue support for BB10 and Whats App followed a short while ago.
And the reason for this I think is obvious - Black Berry's (NASDAQ: BBRY) global market share is dwindling into oblivion year after year, and many companies can't justify the cost anymore.
The operating system was originally called BBX, but this was changed when Black Berry was blocked from using the BBX trademark after legal action from BASIS International, who already used it for their software.
The operating system, as well as two devices, the Z10 (a full touchscreen device), and the Q10 (a device equipped with a physical keyboard), were announced simultaneously around the world on January 30, 2013.
Black Berry has been losing market share just fine by itself.