Thanks mate. I will definitely re-look at the solution design, but long story short, the all_filters is part of a larger form submission (i agree it's not a json, it's an array of objects) and I have to dynamically build multiple elastic-search queries (in true json format).
I really want to understand why your suggestion is not working and what's the underlying difference. I did a thorough search on the forum and noticed, you have dealt with similar scenario here.. and patrick's solution seemed to work for you.
The all_filters at my end is part of a repeat in a server action, while yours seems to be something returned from a query/api-call. And I also notice that the account_id in your above is not within double-quotes anyway.
My form submits the below filters (array of objects).
In my server action, I put the filters through a repeat (named it all_filters) and output the filter_name conditionally if tagged true.
Then, using {{all_filters.groupBy('filter').keys()}}, I want to output an array like this
["Last 24 hours", "Last 48 hours", "Custom"], which is not working 
, may be @patrick can help when he is back.