Camera upload not working

Up- and download of normal files works just fine. But the upload of the camera doesn't resolve in pictures to download. You can check yourself at https://metadata2.systemli.org/

I'm running the latest version:

$ docker ps
CONTAINER ID   IMAGE                                                      COMMAND                  CREATED          STATUS          PORTS                            NAMES
986e9c4957d5   registry.0xacab.org/jfriedli/mat2-quasar-frontend:master   "/docker-entrypoint.…"   7 seconds ago    Up 6 seconds    80/tcp, 0.0.0.0:3002->8080/tcp   mat-web-frontend
9bee48320d84   registry.0xacab.org/jvoisin/mat2-web:v0.7.0                "sh -c 'nginx; uwsgi…"   17 seconds ago   Up 16 seconds   0.0.0.0:3001->8080/tcp           mat2

$ docker image ls
REPOSITORY                                          TAG       IMAGE ID       CREATED        SIZE
registry.0xacab.org/jfriedli/mat2-quasar-frontend   master    734f8a106339   15 hours ago   28.3MB
registry.0xacab.org/jvoisin/mat2-web                v0.7.0    922452dde914   4 months ago   507MB

I get the response {"message": "Unable to clean image/gif"}.