Use the following script

<?php

class Component
{
    public array $items = [];

    public function mount(bool $throw): void
    {
        $this->items[] = ['name' => 'create'];

        // A local reference into the property, freed when this method returns.
        $ref = &$this->items[0];

        if ($throw) {
            try {
                throw new Exception('caught');
            } catch (Exception) {
            }
        }
    }
}

printf("xDebug mode: %s\n", ini_get('xdebug.mode'));

foreach ([false, true] as $throw) {
    $component = new Component();
    $component->mount($throw);

    $isReference = ReflectionReference::fromArrayElement($component->items, 0) !== null;

    // Copy the array and overwrite the copy; the original should never change.
    $copy = $component->items;
    $copy[0] = 'changed in the copy';

    printf(
        "%s exception: items[0] is %sa reference, original items[0] = %s\n",
        $throw ? 'with   ' : 'without',
        $isReference ? '' : 'not ',
        json_encode($component->items[0]),
    );
}

With xdebug off, the output is

xDebug mode:
without exception: items[0] is not a reference, original items[0] = {"name":"create"}
with    exception: items[0] is not a reference, original items[0] = {"name":"create"}

With xdebug on, the output is

xDebug mode: debug,develop
without exception: items[0] is not a reference, original items[0] = {"name":"create"}
with    exception: items[0] is a reference, original items[0] = "changed in the copy"

In the script reflection is used. The reflection is only there to be able to show the text '... is (not) a reference'. Removing the reflection logic does not change the behavior.