I want to make an embed with three buttons in discord.js v12. When I am trying to send the message it returns me [object Object]. What I am doing wrong? Here is my code:

const app = new Discord.MessageEmbed()
.setTitle("my embed here")

let staff = new disbut.MessageButton()
.setStyle('gray')
.setLabel('🔰STAFF')
.setURL('url')
                
let ellas = new MessageButton()
.setStyle('gray')
.setLabel('👮‍♀️POLICE')
.setURL('url')

let ekav = new disbut.MessageButton()
.setStyle('gray')
.setLabel('🚑EKAB')
.setURL('url')

message.channel.send(app, {
    buttons: [staff, ellas, ekav]
});