“Vendor autoload is not found.” ..while file exists and composer is installed

I am currently getting the;

Autoload error

Vendor autoload is not found. Please run ‘composer install’ under application root directory.

Error when trying to load the frontend of my website (fresh install), however I have composer installed within the root directory, an autoload.php exists in /vendor along with all the many subfolders, and the backend loads just fine. Just the frontend is giving this error.

I have tried composer install and composer update which complete successfully and anything else I could find scouring the web, I have done the normal SSH commands for setup:upgrade/di:compile/static-content/reindex/cache:flush, however the issue still persists. Any ideas what the issue could be?

Web Details:

Shared Host

Magento 2.3.7-p4

PHP 7.4.33

Will give any more details needed!