Custom ez-toc-settings[position]

Hello,

I would like to insert the ez-toc right before the second h2 tag of the posts automatically (not possible with the custom option of ez-toc-settings[position]).

I use to use Table of Contents Plus (and I want to migrate to Easy Table of Contents), and the code below used to work without any issue but when I replace the shortcode toc by ez-toc it triggers error 500 :

<?php

function insert_shortcode_before_second_h2($content) {
    // Check if the post is not a page or any other custom type
    if (is_singular('post')) {
        // Check if the post doesn't contain [no_toc]
        if (strpos($content, '[no_toc]') === false) {
            // Find the second occurrence of <h2> tag
            $second_h2_position = strpos($content, '<h2', strpos($content, '<h2') + 1);

            // Find the opening <h2> tag after the second <h2> tag
            $opening_h2_tag_position = strpos($content, '<h2', $second_h2_position);

            // Insert the [toc] shortcode before the opening <h2> tag
            $content = substr_replace($content, '[toc]', $opening_h2_tag_position, 0);
        }
    }

    return $content;
}
add_filter('the_content', 'insert_shortcode_before_second_h2', 9);

As a non-dev, I tried to find a solution with Claude/GPT to work on a code to do this insertion but nothing seems to be working : either the shortcode is not executed (just displayed) or the code triggers a error 500 memory limit (although i ticked the box on the admin page regarding that matter).

Below is the last version that still doesn’t work.. but maybe someone sees something obvious that could fix that ? Maybe it’s useful for others. (I’m not using any website builders)

<?php
// Exit if accessed directly
if (!defined('ABSPATH')) {
    exit;
}

function add_toc_before_second_h2($content) {
    // Only proceed if we're on a single post
    if (!is_single()) {
        return $content;
    }
    
    // Find position of first h2
    $pos1 = stripos($content, '<h2 class="wp-block-heading"');
    if ($pos1 === false) {
        return $content;
    }
    
    // Find position of second h2
    $pos2 = stripos($content, '<h2 class="wp-block-heading"', $pos1 + 1);
    if ($pos2 === false) {
        return $content;
    }
    
    // Build new content
    $content = substr($content, 0, $pos2) . '[ez-toc]' . substr($content, $pos2);
    
    return $content;
}

// Add our function to WordPress content filter
add_filter('the_content', 'add_toc_before_second_h2', 5);

Thanks a lot.