You did not get 1 month Extension but your application is under consideration and you have to come back at the same Immigation Office on the date mentioned in the stamp, 12 May 2022 and get the rest of the time as applied for.
You are free to go one day early and hope all is set and you get the remaining days, it could be that you will be asked to come back on mentioned date.
if you open the website, in the middle is a box with the text "Am I eligible to apply on-line" click on that, fill in the questions and you get the answers,
The rule is crystal clear. a minimum of 12 months foreign deposits into a Thai Bank account on your name of minimum 65.000 Thb.
That you have more than the minimum is good, but does not get you of the hook for having 11 months. BUT you can go to your local Immigration office and ask the officer if he accept this one time mistake.