Performance Linked Reward (PLR) paid will be recovered from F&F settlement

Dear Sir, Performance Linked Reward (PLR) was paid to me on 28-Oct-2021 against my contribution during the FY 2020 – 21. The same day I have resigned from the establishment and now serving notice period. Today on 30-Nov-2021, I have received an email from HR, that my PLR will be recovered from my Full and Final settlement. As I had submitted resignation and serving notice period, I am not eligible for PLR according to the management guidelines. As per my understanding, I am entitled to PLR inclusive of bonus despite my resignation effective from 28-Oct-2021 as I had worked in the establishment throughout the accounting year 2020 – 21. How submitting my resignation in the 3rd quarter of F.Y. 2021 – 22 on dated 28-Oct-2021 make me ineligible for receiving PLR against my contribution during the FY 2020 – 21? The average PLR amount is specifically provided in the Proposed Salary Fixation copy of my offer letter and also according to Reward Letter, the PLR is a perpetual part of my CTC which was paid to me against the service provided by me in the FY. 2020-21. Considering the above, please advice me further course of action from my end.