Fix keys must be str, int, float, bool or None, not Snowflake error

I am trying to write a list of users from a discord server into a json using python, but I keep receiving this error.

Ideally I want to turn my dict {Snowflake(USERID#): Member(user=User(id=Snowflake(USERID#), username='USERNAME', discriminator='#', bot=None), nick=None),

Into a JSON file only containing the bot=none users in a format like this:

{
    "USERID#1": {
        "Username": "USERNAME1"
  },
 "USERID#2": {
        "Username": "USERNAME2"
  },
...
}

Edit:

1. Error text is TypeError: keys must be str, int, float, bool or None, not Snowflake
2. My code to initially pull the data into the dict and attempt to write it to the json is:

    import interactions
    from interactions import Button, ButtonStyle, SelectMenu, SelectOption, ActionRow, spread_to_rows
    import json

    memberslist = await guild.get_all_members()
    print(memberslist)
    membersdict = {Member.id: Member for Member in memberslist}
    with open("playersbackup.json","w") as n:
      json.dump(membersdict,n, indent=4)

from Fix keys must be str, int, float, bool or None, not Snowflake error