The code section @ramset quoted is from the legacy API (purely PHP, no FTL) which is not used since over one year and is subject to be removed rather sooner than later.
You could change it either where it is requested:
https://github.com/pi-hole/AdminLTE/blob/master/scripts/pi-hole/js/index.js#L415
where you would put
$.getJSON("api.php?summaryRaw&getQuerySources=20", function(data) {
or where it is sent to FTL:
https://github.com/pi-hole/AdminLTE/blob/master/api_FTL.php#L146
I'd recommend changing it in the former location as everything will then pass through nicely and the solution will be less hacky.