v3.4.0 and above take advantage of Discord's new slash commands feature. This means you can easily interact with your utility bot within the Discord application.
Wait 1 hour
The utility bot creates "global" commands, which take 1 hour to appear in your server. This is imposed by Discord and there is nothing we can do to change it. Learn more here.
Update your app
Make sure you're using the latest Discord client. Slash commands have been around for a while but really old versions of Discord still might not support them.
Make sure your bot actually has permission to create commands
You'll have to make sure that your bot has the application.commands scope when creating an invite link. If you invited your bot a while ago, just "reinviting" it should work. You don't need to kick your bot. Restart your bot after inviting it again for good measure.
Press "/" on your keyboard
If you've done all of the above, there's a good chance the commands are there and you're just missing them. They should appear in a menu something like the one below. "Apps" dropdowns aren't yet implemented by the utility bot, only commands.