/etc/apache2/mods-available/qos.conf is in libapache2-mod-qos 11.21-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 | <IfModule qos_module>
  # minimum request rate (bytes/sec at request reading):
  #QS_SrvRequestRate                                 120
  # limits the connections for this virtual host:
  #QS_SrvMaxConn                                     100
  # allows keep-alive support till the server reaches 600 connections:
  #QS_SrvMaxConnClose                                600
  # allows max 50 connections from a single ip address:
  #QS_SrvMaxConnPerIP                                 50
</IfModule>
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