don't install mod_php
mod_php should not be installed nor used anymore, use php-fpm instead. might as well enable http2 at the same time:
systemctl stop apache2 a2dismod php7.3 apt-get purge -y libapache2-mod-php* a2enconf php7.3-fpm a2dismod mpm_prefork a2enmod mpm_event a2enmod http2 systemctl start apache2
I suppose an optional switch --with-http2 could be used if enabling http2 is not deemed an appropriate setup to be the default yet, but the php mode should be changed.