Good Day Pare, In this tutorial, I'll teach you how to downgrade your PHP 7.4 to PHP 7.3 on your Ubuntu 20.04 LTS safely. For this, we will use different commands such sudo, apt-get, a2dismod, and a2endmond which we will explain along the road.
This tutorial can be used for downgrading your PHP 7.3 to PHP 7.2 and so on and so forth.
Take a look at the full tutorial here.
https://letscodepare.com/blog/how-to-safely-downgrade-from-php-74-to-php-73-on-ubuntu-20-lts