PHP textarea input multiplies by two and outputs double input - php

Question

Quick rundown:
Everything ran perfectly as it should when I had my own custom textarea field to send data
I had a custom text editor widget for inputs, but tried to add CKEditor for more functionality
When I added CKEditor package (https://ckeditor.com/ckeditor-4/download/?undefined-addons=) the editor was there, but when I clicked "Add" button and sent data, the input was doubled and there was a space between inputs (for example - input was:"test" and output was "test<br><br>test"), as if I put <br> tag and multiplied my input somewhere.
When I stopped trying with CKEditor, I went back to original code and my own original custom text editor, which before worked perfectly. However, to my surprise, it now still doubles the input string, but it doesn't put a <br> tag in between.
In DB the string value is normal and not doubled.
I have no idea how this happened, I've been going over the code for a hour or so now, trying to see if I overlooked something, but I even created a separate file with functioning code, before I was trying with CKEditor in case something broke and I could just replace it with old code and try tomorrow, but now it's messed up and I have no idea how and where.
notifications.php
<form class="form-inline" action="/action_page.php">
</form>
</nav>
<div class="container-fluid m-0 p-0">
<div class="row justify-content-center">
<div class="col-md-10">
<?php if (isset($_SESSION['response'])) { ?>
<div class="alert alert-<?= $_SESSION['res_type']; ?> alert-dismissible text-center">
<button type="button" class="close" data-dismiss="alert">×</button>
<b><?= $_SESSION['response']; ?></b>
</div>
<?php } unset($_SESSION['response']); ?>
</div>
</div>
<div class="row">
<div class="">
<?php
$query = 'SELECT * FROM crud';
$stmt = $conn->prepare($query);
$stmt->execute();
$result = $stmt->get_result();
?>
<table class="table table-hover" id="data-table">
<tbody>
<?php while ($row = $result->fetch_assoc()) { ?>
<tr>
<td></td>
<td class="pt-2"><?=
$longString=$row['name'];
$link = $row['id'];
$longStringshortcut = strlen($longString);
//echo substr($longString, 0, 100).'... Read More';
if ($longStringshortcut > 250) {
echo substr($longString, 0, 250).".. <a href='details.php?details=$link'><strong>Preberi več...</strong></a>"; }
else {
echo $longString;
}
?>
Details
Delete
Edit
</td>
</tr>
<?php } ?>
</tbody>
</table>
<div class="col-md-4 p-0">
<h5 class="">Add notification:</h5>
<form action="action.php" method="post" enctype="multipart/form-data">
<input type="hidden" name="id" value="<?= $id; ?>">
<div class="form-group">
<textarea name="name" value="<?= $name; ?>" class="form-control" placeholder="This is the default text" required></textarea>
</div>
<div class="form-group">
<?php if ($update == true) { ?>
<input type="submit" name="update" class="btn btn-success btn-block" value="Change notification">
<?php } else { ?>
<input type="submit" name="add" class="btn btn-primary btn-block" value="Add">
<?php } ?>
</div>
<div class="form-group">
<input type="hidden" name="oldimage" value="<?= $photo; ?>">
<input type="file" name="image" class="custom-file">
<img src="<?= $photo; ?>" width="120" class="img-thumbnail">
</div>
</form>
</div>
</div>
</div>
</div>
action.php
<?php
session_start();
include 'config.php';
$update=false;
$id="";
$name="";
$photo="";
if(isset($_POST['add'])){
$name=$_POST['name'];
$photo=$_FILES['image']['name'];
$upload="uploads/".$photo;
$query="INSERT INTO crud(name,photo)VALUES(?,?)";
$stmt=$conn->prepare($query);
$stmt->bind_param("ss",$name,$upload);
$stmt->execute();
move_uploaded_file($_FILES['image']['tmp_name'], $upload);
header('location:index.php');
$_SESSION['response']="Successfully Inserted to the database!";
$_SESSION['res_type']="success";
}

Answer 1

The problem was with the <?= syntax (echoing), <?php solved it.