Htaccess Mod Rewrite Not working for Pretty URL - apache

Question

I feel like such a tool for having to post this question, but for the life of me, I cannot figure out how to resolve my issue. (I've also read/tried previous posts but none have helped me)
I'm trying to turn https://mywebsite.com/article.php?slug=pretty-url to https://mywebsite.com/article/pretty-url
The problem I'm having is the $_GET method is not recognizing the slug, so it's giving me a 404 error. The slug is definitely in my database. I'm not sure why I cannot retrieve it.
Below is my htaccess code and my php code to call the page.
Htaccess Code:
<IfModule mod_rewrite.c>
Options +FollowSymLinks
RewriteEngine On
# Redirect www urls to non-www
RewriteEngine on
RewriteCond %{HTTP_HOST} ^www\.mywebsite\.com [NC]
RewriteRule (.*) https://mywebsite.com/$1 [L]
RewriteEngine On
RewriteCond %{SERVER_PORT} 80
RewriteRule ^(.*)$ https://mywebsite.com/$1 [L]
ErrorDocument 404 /404.php
#Pretty URL for Blog
RewriteRule ^article/([0-9a-zA-Z]+) article.php?slug=$1
#Rewrite for certain files with .php extension
RewriteRule ^about$ about.php
RewriteRule ^services$ services.php
RewriteRule ^portfolio$ portfolio.php
RewriteRule ^blogs$ blogs.php
RewriteRule ^tutorials$ tutorials.php
RewriteRule ^contact$ contact.php
RewriteRule ^privacy-policy$ privacy-policy.php
RewriteRule ^terms-of-service$ terms-of-service.php
RewriteRule ^sitemap$ sitemap.php
</IfModule>
PHP Code on the article.php page:
//Get the blog. Only blogs that are published
$slug = $_GET['slug'];
$publish = intval(1);
//Query the database
$sql = "SELECT * FROM blogs WHERE publish = $publish AND slug = $slug";
//Execute the query
$stmt = $db->query($sql);
$row = $stmt->fetch(PDO::FETCH_ASSOC);

Answer 1

([0-9a-zA-Z]+) will not capture pretty-url because the group doesn't allow for hyphens. Change that to ([A-Za-z0-9-]+) and add [L] to the end of that line.
Also, for the sake of doing things properly, remove the second and third calls to RewriteEngine On.

Answer 2

Never apologise for a question! If you're stuck, we will try to help.
What you need in your htaccess is the following:
RewriteEngine On
RewriteRule ^([^/]*)\.html$ /article.php?slug=$1 [L]
That should change your url to https://mywebsite.com/pretty-url.html