Running into this issue myself at the moment- seems like it’s in alphabetical order, but from the initial name of the fields and ignoring later changes. ie. if you created fields called Beta and Alpha, then renamed Alpha to Gamma, it would still output in order Gamma Beta. Would be nice to be able to change this (though admittedly it’s not a massive issue)
Edit: Just noticed Emmanuel confirmed this is the case elsewhere (Get data api has old table names) and it could break existing apps if changed, which is fair enough.