I get errors on my account.

[nanasina8]

I also created an account on submarin.online to embed it and tried to embed it, but couldn't. I used the same method to embed your Haiku Bot and it worked. Did I need to do anything else than what is written in the "README.md"?

[NarixHine]

Could you please make sure that the user_id you've put in the URL is not your user name (@xxx) but your ID (e.g. 9hdihe2rmm) which you can find in the settings? This should fix the issue.

[nanasina8]

I used the id shown there but could not
<iframe src="https://missbed.narix.link/timeboard/submarin.online/9l078h5ok1" width="100%" height="1000"></iframe>
Is there a problem with this code?

[NarixHine]

Currently I doubt it is caused by a bug within the MFM package published by Misskey, I will dig deeper into this later when I have got some time.