customization – filter higher and decrease case characters in Auto tag hyperlink code?

Query:
How one can filter uppercase and lowercase when the phrase ‘tag’ is written in lowercase?

and vice versa, filter the phrase ‘tag’ which is written in capital letters?

This is the code I acquired from a plugin that hasn’t been up to date in just a few years.

perform auto_link_tags($content material){

//$post_id = get_the_ID();
$post_tags = get_the_tags();

if ($post_tags) {
    $i = 0;
    foreach($post_tags as $tag) $)))b~i";
        $tag_url = get_tag_link($tag->term_id);
        $tag_html[$i] = '<a href="' . $tag_url . '" title="$1">$1</a>';
        $i++;
    
    $content material = preg_replace($tags, $tag_html, $content material);
}

return $content material;}