How can I pass an array variable containing my images in the form of DataURL to my server?

Example of array
["aug.jpg,data:image\/jpeg;base64,\/9j\/4AAQSkZJRgABAQAAAQABAAD\/4gIoSUNDX1BST0ZJTEUAAQEAAAIYAAAAAAIQAABtbnRyUkdCIFhZWiAAAAAAAAAAAAAAAABhY3NwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAQAA9tYAAQAAAADTLQAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAlkZXNjAAAA8AAAAHRyWFlaAAABZAAAABRnWFlaAAABeAAAABRiWFlaAAABjAAAABRyVFJDA......]

I have tried to JSON.stringify the value of the array on the front end and attempt to json_decode on the backend but it results in an error :

"error_log() expects parameter 1 to be string, array given"

I have also tried creating a hidden input field for each array of images(dataURL) that I have and serializing the value but when receiving the value of the input on the server, i am unable to convert it back to an array.

for (let k = 0; k < Object.keys(savedImageFilesArray_complex_form).length; k++) {
    console.log("Appending image");
    var img_item = (savedImageFilesArray_complex_form[k]);
    //img_item=JSON.stringify(['testing','testing123']);

    var input = document.createElement("input");
    input.type = "hidden";
    input.name = "finalImageFilesComplexForm"+k+"[]";
    input.class = 'serializeImages' +k;
    input.value = img_item
    appendArea.appendChild(input);

    $('.serializeImages'+k).serialize();
}

(Edited with server code)

Appended below is the value that i am receiving on the $request on the server end.

When trying to json_decode the value, it results in the error as mentioned earlier with the parameter 1 being a string rather than an array

  error_log(json_decode($request['finalImageFilesComplexForm0'][0]));