Apple Mail Spell Check - Strange Functionality

I am finding that the default spell checker on Apple mail has some really strange functionality.

On a Macbook Air, Ventura OS.

Here's what I've noticed:

1. When replying to an email, it spell checks the indented text from the previous email. Not in any way useful.
2. Stopping the spell checker by closing the window works in an unpredictable way. Sometimes, the email is sent immediately. Other times it isn't and you need to hit the send button again. I've just noticed a third behaviour which I find quite bizarre. I closed the spell check window because I realised I wanted to do further edits before sending. I was working away on this when the spell check window reappeared. I ignored it and kept editing. Whilst in the middle of editing, the email spontaneously sent itself without me clicking anything...

I've worked with email for years and with a number of different email clients. New to Apple, and have never seen such strange and unpredictable functionality.

Obviously you don't want emails being sent before you are absolutely sure they are correct, and spell checking is an important part of this.

Any assistance greatly appreciated!

Mark