PHP 8.0.27 SQL Permission Denied (can connect via other clients)

Hello,
I'm having trouble connecting to my SQL database from my Centos 7 VPS. I have tried using both mysqli and PDO, both are returning permission denied. I have copied the connection string from an identical OVH system and checked everything hundreds of time but I keep getting permission denied. I have managed to connect via phpmyadmin and through TablePlus with no issues, I just can't acccess via php.
The VPS ip is whitelisted and the user account has been granted administrator for all databases. I have also tried using the SFTP account and still, permission denied. If anyone has any pointers on what to check that would be great. Thanks.