Docker: PHP Startup: Unable to load dynamic library 'pgsql'

I'm trying to run a CodeIgniter application (PHP framework) on a Docker container and I'm getting this error:

Message: PHP Startup: Unable to load dynamic library 'pgsql' 
(tried: /usr/local/lib/php/extensions/no-debug-non-zts-20190902/pgsql 
(/usr/local/lib/php/extensions/no-debug-non-zts-20190902/pgsql: 
cannot open shared object file: No such file or directory), 
/usr/local/lib/php/extensions/no-debug-non-zts-20190902/pgsql.so 
(/usr/local/lib/php/extensions/no-debug-non-zts-20190902/pgsql.so:
 cannot open shared object file: No such file or directory))

And therefor, this one:

Message: Call to undefined function pg_pconnect()

This is my Dockerfile:

FROM php:7.4.1-apache
RUN apt-get update && apt-get install -y libpq-dev
RUN docker-php-ext-configure pgsql -with-pgsql=/usr/local/lib/php/extension/pgsql
RUN docker-php-ext-install pdo pdo_pgsql

COPY . /var/www/html
COPY php.ini-production /usr/local/etc/php/php.ini

RUN service apache2 restart

EXPOSE 80

On the php.ini I have the extension enabled like this:

;extension=pdo_odbc
extension=pdo_pgsql
;extension=pdo_sqlite
extension=pgsql
;extension=shmop

And if I visit my info.php site, I see the extensions are enabled:

I also see, that my php.ini is saved correctly:

I have tried a lot of suggestions from different posts, but havn't been successful at all.

Does someone know where the issue might be?

Thanks,