Announce to every joining users that you moved to greener pastures (you need the "irc" Python3 package to run it). Beware, I got a server klined after using it.

leebot.py

import argparse

try:
    import irc.client
except ImportError:
    exit("You need the IRC package to run this bot: pip3 install irc")


def main():
    argparser = argparse.ArgumentParser(description="\"pick up that chan, leetizen\"")
    argparser.add_argument(
        "old_channel",
        help="Channel to join and monitor",
    )
    argparser.add_argument(
        "nick",
        help="Bot name"
    )
    argparser.add_argument(
        "new_channel",
        nargs="?",
        help=(
            "Channel name on the new server to advertise"
            " (defaults to old channel name)"
        ),
    )
    argparser.add_argument(
        "--new-server",
        default="irc.libera.chat",
        help="New server hostname to advertise (defaults to irc.libera.chat)"
    )
    argparser.add_argument(
        "--new-port",
        type=int,
        default=6697,
        help="New server port to advertise (defaults to 6697)"
    )
    args = argparser.parse_args()

    bot = Leebot(args.old_channel, args.nick, args.new_channel or args.old_channel,
            args.new_server, args.new_port)
    bot.run()



class Leebot(irc.client.SimpleIRCClient):

    MSG = (
        "Hi {target}! This channel has moved to {ns} (port {np}), under the "
        "name {nn}"
    )

    def __init__(self, old_chan, nick, new_chan, new_server, new_port):
        super().__init__()
        self.old_chan = old_chan
        self.nick = nick
        self.new_chan = new_chan
        self.new_server = new_server
        self.new_port = new_port

    def run(self):
        self.connect("irc.freenode.net", 6667, self.nick)
        try:
            self.start()
        except KeyboardInterrupt:
            print("Bye!")

    def on_welcome(self, connection, event):
        connection.join(self.old_chan)

    def on_join(self, connection, event):
        joined = event.source.nick
        if joined != self.nick:
            self.announce(joined, event.target)

    def announce(self, target, channel):
        message = Leebot.MSG.format(
            target=target,
            ns=self.new_server,
            np=self.new_port,
            nn=self.new_chan
        )
        self.connection.privmsg(channel, message)


if __name__ == "__main__":
    main()