Memory usage of the worker process keeps increasing when HTTP/2 requests are repeatedly sent over the same TCP connection

Issue

If an Apache HTTPD Server continues to proxy h2 requests sent from the same TCP connection using mod_http2 and mod_proxy_http2, the memory usage of the worker process keeps increasing.

apache      6328  0.4  0.2 1810168 17512 ?       Sl   03:17   0:00 /opt/rh/jbcs-httpd24/root/usr/sbin/httpd -DFOREGROUND  // 2.4.57 SP6: immediately after httpd startup
...
apache      6328 33.9  2.6 1818040 207176 ?      Sl   03:17   6:09 /opt/rh/jbcs-httpd24/root/usr/sbin/httpd -DFOREGROUND  // 2.4.57 SP6: after proxying one million HTTP/2 requests