As someone with over a decade of experience in web development, I am well-versed in the demanding and time-sensitive nature of upgrades like the one you require, particularly when it comes to PHP. My thorough knowledge of languages including PHP, as well as frameworks and libraries like Angular, React and Vue.js means that I can ensure a seamless transition from PHP 5.6 to PHP 8.3 for your lyrics database.
Moreover, my extensive experience with databases such as MySQL means I am fully capable and familiar with standard PHP extensions like MySQLi_connect or PDO that your hosting provider has recommended. I will address the deprecated 'mysql_connect' function effectively to bring your website back to functionality, ensuring zero compromise on its existing features or functionalities.
In conclusion, let's not allow three days of downtime to turn into more – instead, let me work closely with you to guarantee swift restoration of your SE position by getting Superseventies dot com up-and-running again. My skills, understanding, and commitment to achieving top-notch results make me an ideal candidate for this project. Thanks for the opportunity; I look forward to hearing from you soon!