You should upload it to the right dir for your php version. To know what is the right extension dir used by php 7.4:
php7.4 -i | grep extension_dir | awk '{print $NF}'
Keep in mind that if you edited php conf from Hestia Web UI, you are modifying the conf for ALL your installed PHP versions so remove the conf added, save it and now edit /etc/php/7.4/fpm/php.ini manually to add the right conf for your extension.