Android – Send JSON php

I am having problems sending a JSON from a PHP and MySQL webService, I leave the query code and the assoc fetch, the query has already been checked and it is correct, in phpMyAdmin it makes me perfect, the problem is that when I receive the JSON on Android I receive things that should not be part of the JSON:

$ query = "SELECT` id`, `activity`,` place`, `date` FROM` plans` WHERE `user` = '". $ user. "' ORDER BY` id` DESC ";

$ result = mysqli_query ($ mysqli, $ query);
$ rawdata = array ();
$ i = 0;

while ($ row = mysqli_fetch_array ($ result))
{
    $ rawdata[$i] = $ row;
    $ i ++;
 }

echo json_encode ($ rawdata);

and this is what I receive in android according to the log:

{"0": "1", "id": "1", "1": "Test", "activity": "Test", "2": "Madrid", "place": "Madrid", " 3 ":" 01/12/2019 "," date ":" 01/12/2019 "}

is putting things that are not, should be

{"id": "1", "activity": "Test", "place": "Madrid", "date": "01/12/2019"}

I do not know without are the bars (/), if it is the utf8 encoding, …

Any ideas?

Thank you very much, greetings