AttributeError: 'Message' object has no attribute 'message'

@bot.command() 
async def level(ctx) : 
    file = openpyxl.load_workbook("level.xlsx")
    sheet = file.active
    exp = [10, 20, 40, 70, 110, 160, 220, 290, 370, 460, 560]
    i = 1
    while True :
        if sheet["A" + str(i)].value == str(ctx.message.author.id) :
            sheet["B" + str(i)].value = sheet["B" + str(i)].value + 2.5
            if sheet["B" + str(i)].value >= exp[sheet["C" + str(i)].value - 1] :
                sheet["C" + str(i)].value = sheet["C" + str(i)].value + 1
                await ctx.send("Level UP !!\n현재 레벨 : " + str(sheet["C" + str(i)].value) + "\nExp : " + str(sheet["B" + str(i)].value))
            file.save("level.xlsx")
            break
        if sheet["A" + str(i)].value == None :
            sheet["A" + str(i)].value = str(ctx.message.author.id)
            sheet["B" + str(i)].value = 0
            sheet["C" + str(i)].value = 1
            file.save("level.xlsx")
            break
        i += 1

I am creating a system that automatically builds up exps when any chat is chatted and level up when certain exps are filled.

When using @bot.command(), it worked well, but I must enter level to make it work, and when you switch to @bot.event and chat any time, the following error appears:

AttributeError: 'Message' object has no attribute 'message'

How can I fix the error?