Notice period Advice

Hi Guys,

Need your professional advice here

So I had resigned from my company early this month, and kept the last working day on December 5th, which was accepted. A week after my resignation, I faced severe backache and visited the doctor. The doctor suggest a weeks rest and a month of wfh post, I submitted all the required medical certificates to my manager. Post this my manager stated that he will consider an early release option with the last date as next week, he will pay me only till my last date. I wanted to check if this is ethical, considering it will be a loss of pay of almost 2months. What could be my next steps here, as they didn't even ask me for my opinion but went ahead and processed this. I have worked here for almost 2years.