The issue occurs as well on Ubuntu 18 and Ubuntu 20 which are installing Apache update from default OS repositions. So far consider one of the following workarounds:
1. Switch to FastCGi instead of PHP-FPM
2. Downgrade Apache to previous version:

    Find previously installed Apache version, based on below output you may see it is "2.4.41-4ubuntu3"
    # apt-cache showpkg apache2 | tail
    2.4.41-4ubuntu3.5 - httpd-cgi (= ) httpd (= )
    2.4.41-4ubuntu3 - httpd-cgi (= ) httpd (= )
    Reverse Provides:
    Now downgrade Apache to previous version, replace the value for the "version" variable with the one you found on previous step:
    # export version="2.4.41-4ubuntu3"; apt-get install apache2=$version apache2-utils=$version apache2-data=$version apache2-bin=$version
    Put it on hold until fix is available:
    # apt-mark hold apache2