Page refreshes twice after updating datas - php

Question

Update Information first:
The cause for question is found. For Solution/Reason see end of this Posting ...
Here is some PHP code to update a data row in a sqlite DB using PDO:
$db = new PDO("sqlite:$db_name");
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$update_data = array(
'animal' => 'cow',
'name' => 'Mary',
'age' => '4',
);
$stmt = $db->prepare( "UPDATE $db_table SET animal = :animal, name = :name, age = :age WHERE id = 48 " );
$stmt->execute($update_data);
echo $stmt->rowCount();
The (to me) strange behaviour is, that the page in the browser loads the page twice when this code is excuted.
NOTE: This happens only if the datas in the DB changed. If the update data are identical with DB data (so there is no change in the DB) the page only loads one time.
The Effect is the same:
when only this the code is on a plain PHP page (= initalize a new page load -> the page loads correct -> the DB action happens -> page automatic refreshs to load second time ?why?)
or if I initalize the code by a form request (= submit form -> action leads to the same page -> page loads correct -> afer processing POST data the code with this DB action is executed -> page automatic whants reload second time ?why?)
This effect does not exist when I run the same code on a MySql DB (tested on a Maria DB):
$db = new PDO("mysql:mysql:host=localhost;dbname=tst_animals", 'admin', 'admin' );
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$update_data = array(
'animal' => 'cow',
'name' => 'Mary',
'age' => '4',
);
$stmt = $db->prepare( "UPDATE $db_table SET animal = :animal, name = :name, age = :age WHERE id = 5 " );
$stmt->execute($update_data);
echo $stmt->rowCount();
This code is executed after the page has loaded without a automatic page refresh.
Can anyone explain the strange behaviour to me:
What in this code is the reason for the automatic page reload?
How can I avoid the automatic page reload (the Idea is: the DB action executes and nothing on the page itself changes)?
Thxs for all answers.
PS:
Please notice that this has nothing to do with try{...}catch(){...}. Using the code with try/catch shows same effect. I just reduced the code for testing and simplifying the issue here and tested it with/without try/catch as well.
The tested behaviour is the same if the code with the DB action is executed before (or even after) something has written to the page.
UPDATE AND SOLUTION
As in the comments was a remark that the code does not work here the working example for 'PDO sqlite', - I only added the variable settings, sorry for the little abstraction:
<?php
$db_name = "D:/xampp/htdocs/devClassForm/system/sqlite/db_animals.sqlite";
$db_table = "animals";
$db = new PDO("sqlite:$db_name");
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$update_data = array(
'animal' => 'cow',
'name' => 'Mary',
'age' => '4',
);
$stmt = $db->prepare( "UPDATE $db_table SET animal = :animal, name = :name, age = :age WHERE id = 48 " );
$stmt->execute($update_data);
$stmt->rowCount();
DB table settings are:
[id, integer, autoincrement, primary key]
[animal, text]
[name, age]
[age,integer]
When testing please fill database and adapt id number in statement to your settings.
The plain code indeed works proper as it is. I copied it direct one to one from testing file , - but concerning to the insistings comments I checked the code once more and found the solution for the very strange and irritationg behaviour:
When I tested I used VS Code with Live Server Extension. This Setup in Firefox (not testet with Chrome...) indeed causes the auto refresh of the page (checked in the Server logs).
Deactivating this extension the code works as well, updates db data and the page only loads once.
Thxs for the help :-)
(I suggest to let this posting stay here and not to delete it even it is not really a coding issue. Maybe this information about the testing setup helps somone else some time to save time.)