OK just seen you've changed it to show leaving Thailand and not entering as I thought you were trying to do.
In which case, can't they put you on an earlier flight? If they can't, and you have to leave on 30 November, then you'll have to book with another airline.
Alternatively, if you can leave on 1 December then you can always apply for the unable to travel due to covid extension to cover the additional day so you don't get any comment put in your passport.
don't think I've come across that before I have to say, hopefully some others will have.
However, the under consideration part is normal in some of the immigration offices. I wouldn't worry about, I haven't read of anyone getting the under consideration stamp and then being denied the rest of the extension.