So I found the answer by myself. It was rather simple. The localhost server I was running uses PHP 8.0, while the website I was trying to migrate runs on WordPress 5.4.1 using PHP 7.3. All I had to do was to configure xampp to run PHP 7.3 on that particular project and done. The site showed up without any issue.
So I’m debating between deleting the question or leaving it up, because it was a dumb problem, but also it’s a pretty good educative tool of why you should always check that your localhost server uses the same versions of the live server.