Do not disturb always on at sturtup

There may be something that starts when you boot normally, or when you log in to your account, that causes this.

I gather that you want this to be completely off.

I hope we can solve the present issue, but in the meantime: you could just simply set to be on from, say, 3am to 3h05am.

Create a new admin account.

Make sure that Do not Disturb is off.

Restart your mac and log in straight to this new account. Is DND on or off?

You could start by looking at your Login Items to see if something stands out.

Please run Etrecheck and post its full report here. Use the "additional text" button and paste the report into the text box.

Try restarting in Safe Mode, then turn off Dot Not Disturb and restart normally again. Same problem?

Try resetting NVRAM.