Employer Puts employee on PIP in Resignation period - Is this something legal that the employer can do?

Hi, I'm an employee working in Bangalore with a renowned company for 18 months now, wherein I'd resigned in February, and in the month of March, my employment had to end with the employer. The employer asked to extend my notice period verbally for which even I agreed as it was the start of the pandemic situation and they didn't speak about relieving me since then till July.
In the month of July, they come up stating that there have been performance issues and has put me on PIP and wants to terminate the employment without giving any employment benefits. Is this something legal that the employer can do?

I don't know why some people fail to give complete details of their employment when they raise certain contentious issues about their employment. It is imperative that the capacity of employment i.e., whether workman, supervisory with a monthly salary exceeding Rs.10000/= or managerial should be mentioned to enable others to assess the situation explained, possible consequences to be anticipated and the approriate remedial measures to be suggested.