exporting/importing is different and using local JSON.
Export/Import creates an array in JSON that can hold multiple groups this is the source of the extra bracket.
Local JSON stores a single group.
I’m not sure I understand your process.
1) create an acf-json folder
2) save field groups which creates json files
3) commit changes to git repo
4) pull changes from git repo
5) upload json changes to server
6) syn field groups
However, as far as 6 goes, I only do this on my dev site. You should only sync field groups on the site where you make changes. These groups should not exist in the DB to be edited on sites where they will never be edited. Unless you plan on editing the field groups on staging/production the only place they should exist is as JSON files.
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