Message detection in discord.py==2.0.0

import discord
from discord import app_commands

class aclient(discord.Client):
    def __init__(self):
        super().__init__(intents=discord.Intents.default())
        self.synced = False

    async def on_ready(self):
        await self.wait_until_ready()
        if not self.synced:
            await tree.sync(guild=discord.Object(id=748244591387607111))
            self.synced = True
        print('---------------------Bot is ready---------------------')


client = aclient()
tree = app_commands.CommandTree(client)

# some slash commands here

# message detection here

client.run('MYTOKEN')

I've already figured out the slash command part, but the message detection doesn't seem to work. In discord.py<2.0.0 I used the following code:

@client.event
async def on_message(message):
    # do stuff here

However in discord.py==2.0.0 it doesn't seem to work. I'm not sure if this is a problem related to the version or the fact that I defined the client through a class. Help would be appreciated!