We apologize for the instability of composr.app and appreciate your patience. We are working on the statistics addon and trying to find an optimal way to store and render data. Unfortunately, we have yet to find a solution that can handle the traffic (and therefore, tens of millions of statistical records) of composr.app. We're working hard on one.
#5920 - Catalogue field type "An uploaded picture" does not allow .svg
https://hackernoon.com/the-dangers-of-svg-files-a-lesser-known-vector-for-xss-attacks
If you wish to change this, you can add svg to the list of allowed image extensions in your site configuration.