I’m failing to use my own custom module to format log entries coming from :ssl application, under OTP 25. Here’s my code:

require Logger

defmodule MyFormatter do
  def format(level, message, _timestamp, _metadata) do
    ['[', level, ']', 'Simon says:', message, ?\n]
  end
end

:inets.start()
:ssl.start()

:ok = :logger.update_handler_config(:ssl_handler, :formatter, {MyFormatter, %{}})

:httpc.request('https://github.com')

The output still prints what looks like a default message:

11:50:31.761 [warning] Description: ~c"Server authenticity is not verified since certificate path validation is not enabled"
     Reason: ~c"The option {verify, verify_peer} and one of the options 'cacertfile' or 'cacerts' are required to enable this."

If I check handler configuration via :logger.get_handler_config(:ssl_handler) it looks as expected:

{:ok,
 %{
   config: %{
     burst_limit_enable: true,
     burst_limit_max_count: 500,
     burst_limit_window_time: 1000,
     drop_mode_qlen: 200,
     filesync_repeat_interval: :no_repeat,
     flush_qlen: 1000,
     overload_kill_enable: false,
     overload_kill_mem_size: 3000000,
     overload_kill_qlen: 20000,
     overload_kill_restart_after: 5000,
     sync_mode_qlen: 10,
     type: :standard_io
   },
   filter_default: :stop,
   filters: [
     filter_non_ssl: {&:logger_filters.domain/2, {:log, :sub, [:otp, :ssl]}}
   ],
   formatter: {MyFormatter, %{}},
   id: :ssl_handler,
   level: :debug,
   module: :logger_std_h
 }}

What I might be doing wrong?