Why "on a tout découvert et partagé ensemble"?

Hi Sean, 

All together would be -

tous ensemble 

here it is -

tout ...ensemble = everything ... together

not quite the same.

Here is a Kwiziq lesson on this topic:

https://kwiziq.learnfrenchwithalexa.com/revision/grammar/tout-tous-and-toute-toutes-all-all-of-them-the-whole-indefinite-pronouns

Hope this helps!