Почему не работает запись гильдий в json файл disnake, python?

    import disnake
import os
from disnake.ext import commands
import json

def get_server_prefix(bot, message):
    with open("prefix.json", "r") as f:
            prefix = json.load(f)

    return prefix[str(message.guild.id)]



bot = commands.Bot(command_prefix=get_server_prefix, help_command=None, intents=disnake.Intents.all())
bot.remove_command('help')


@bot.event
async def on_ready():
  print(f"Бот {bot.user} работает!")
  activity = disnake.Activity(type=disnake.ActivityType.listening, name=F"...")
  await bot.change_presence(status=disnake.Status.do_not_disturb, activity=activity)
        
@bot.event
async def on_guild_join(guild):
    with open("prefix.json", "r") as f:
            prefix = json.load(f)
    
    prefix[str(guild.id)] = "bt."

    with open("prefix.json", "w") as f:
          json.dump(prefix, f, indent=4)

@bot.event
async def on_guild_remove(guild):
    with open("prefix.json", "r") as f:
            prefix = json.load(f)
    
    prefix.pop(str(guild.id))

    with open("prefix.json", "w") as f:
          json.dump(prefix, f, indent=4)

     

@bot.command(administrator=True)
async def load(ctx, extension):
    extension = extension.lower()
    bot.load_extension(f'cogs.{extension}')
    await ctx.send(f'{extension} загружен')


@bot.command(administrator=True)
async def unload(ctx, extension):
    extension = extension.lower()
    bot.unload_extension(f'cogs.{extension}')
    await ctx.send(f'{extension} отгружен')

@bot.command(administrator=True)
async def reload(ctx, extension):
    extension = extension.lower()
    bot.unload_extension(f'cogs.{extension}')
    bot.load_extension( f'cogs.{extension}' )
    await ctx.send(f'**{extension}** **перезагружен**')


for fn in os.listdir('./cogs'):
  if fn.endswith('.py'):
    bot.load_extension(f"cogs.{fn[:-3]}")
                
TOKEN = "..."

bot.run(TOKEN)