php - json_encode fails because of Unknown charactar

one text

I have this array :

[responses] => Array
                        (
                            [0] => Array
                                (
                                    [date] => 2021-07-09 15:16:53
                                    [text] => [Resume session??????%
1 Yes
2 No, CANCEL, SEND]
                                )

                        )

[text] is taken from USSD response and it shows Resume session? on phone but inside the array it is Resume session??????%. That's where json_encode fails.

How to fix that !?