Is /etc/sysctl.conf ignored in Monterey (12.0.1)?

The current shell is /bin/zsh

man sysctl | more gets:

SYSCTL(8)                    System Manager's Manual                   SYSCTL(8)

NAME
     sysctl – get or set kernel state

SYNOPSIS
     sysctl [-bdehiNnoqx] name[=value] ...
     sysctl [-bdehNnoqx] -a

DESCRIPTION
     The sysctl utility retrieves kernel state and allows processes with
     appropriate privilege to set kernel state.  The state to be retrieved or
     set is described using a “Management Information Base” (“MIB”) style name,
     described as a dotted set of components.

     The following options are available:

     -A      Equivalent to -o -a (for compatibility).

     -a      List all the currently available non-opaque values.  This option is
             ignored if one or more variable names are specified on the command
             line.

:

I assume you wanted to see whether the variables net.inet6.ip6.use_tempaddr and net.inet6.send.opmode show up in the man pages. I scrolled through the whole text and unfortunately they doesn't.

I think there isn't a problem with the path. All commands are executable. The values for the both variables are visible:

me@Computer~ % sysctl -a | grep net.inet6.send.opmode
net.inet6.send.opmode: 1

me@Computer~ % sysctl -a | grep net.inet6.ip6.use_tempaddr
net.inet6.ip6.use_tempaddr: 1

I tried to set them to zero, but that's very weird, because it says set to 0, but it is still 1:

me@Computer~ % sudo sysctl -w net.inet6.ip6.prefer_tempaddr=0
Password:
net.inet6.ip6.prefer_tempaddr: 1 -> 0
me@Computer~ % sysctl -a | grep net.inet6.ip6.use_tempaddr   
net.inet6.ip6.use_tempaddr: 1
me@Computer~ % sudo sysctl -w net.inet6.ip6.prefer_tempaddr=0
net.inet6.ip6.prefer_tempaddr: 0 -> 0
me@Computer~ % sysctl -a | grep net.inet6.ip6.use_tempaddr   
net.inet6.ip6.use_tempaddr: 1