Steps to reproduce the issue

Install Joomla 4 on a server that requires the use of the FTP Layer (see #31857)

Attempt to install a fully Joomla 4 compatible extension

Expected result

Extension is installed.

Actual result

FTP Log shows no attempt to extract the zip file after download:

Thu Apr 22 17:21:16 2021 [pid 75088] CONNECT: Client "::ffff:127.0.0.1"
Thu Apr 22 17:21:16 2021 [pid 75087] [www-ftp] OK LOGIN: Client "::ffff:127.0.0.1"
Thu Apr 22 17:21:16 2021 [pid 75089] [www-ftp] OK UPLOAD: Client "::ffff:127.0.0.1", "/var/www/html/tmp/pkg_akeeba-8.0.4-core.zip", 2025132 bytes, 120611.57Kbyte/sec
Thu Apr 22 17:21:16 2021 [pid 75089] [www-ftp] OK DELETE: Client "::ffff:127.0.0.1", "/var/www/html/tmp/pkg_akeeba-8.0.4-core.zip"

System information (as much as possible)

Additional comments