Cant install PHP 7.2 on Ubuntu 20.04

Follow the steps described below

1: add the PPA maintained by Ondrej Surý

sudo add-apt-repository ppa:ondrej/php

2: install PHP versions 7.2

sudo apt install php7.2

3: Select the standard version of PHP

sudo update-alternatives --set php /usr/bin/php7.2

4: Disable version 7.4 or the one you are using

sudo a2dismod php7.4

5: enable version 7.2

sudo a2enmod php7.2

6: Restart the apache server

sudo systemctl restart apache2

Hope this helps!

You could try adding the eoan/main PPA... Although, this is likely not a preferred route to follow.

$ sudo su
$ cp /etc/apt/sources.list /etc/apt/sources.list.bkp
$ echo "deb http://ppa.launchpad.net/ondrej/php/ubuntu eoan main" >> $ /etc/apt/sources.list
$ apt update
$ apt install php7.2 php-pear php7.2-gd php7.2-dev  php7.2-zip php7.2-mbstring php7.2-mysql php7.2-xml php7.2-curl
$ exit