Earned Leave cancellation by Company that were kept a side beyond 30days

I work in SW company based out in India(multiple locations).
1)7-8 years back company changed leave policy by limiting the Earned(Privilege) Leave accumulation to 30 days and said beyond 30 days can not be carried forwarded & will be lapsed. The leave accumulated beyond 30 days were moved to a pool called Extended PL pool and limited that pool to 45 days. They initially allowed to use this extended PL pool also, but after 2-3 years they added restrictions that this leave pool can only allowed after consuming all other leave (like CL, PL in current year pool) + medical/special situations + with multiple level of approvals .

Is this kind of restrictions allowed legally on PL & conformance to state labor laws like Karnataka ?

2)Later company has gone through multiple acquisitions but the above extended PL pool continued till this year end.
Recently company said that from 1st Jan they are cancelling this extended PL pool also and said they will provide additional leave for Medical/special situations (+ with multiple level of approvals ) from a Special leave pool which applies to all employees. This Special pool was created from PL donations from employee during COVID time.

Is this extended PL pool cancellation allowed legally & conformance to state labor laws like Karnataka ? How should one approach such situation to protect their hard earned PL leave?

First of all, the leave concerned is earned by the employees and that is a personal right accrued to them, it cannot be just taken away by an order to that effect. On availing or its utilisation reasonable conditions can be imposed but it cannot be said to be extinguished altogether all of a sudden. That is an unreasonable condition and is hence inequitable.
As regards approaching the issue, the employees concerned shall make individual or collective representation against such a move. If the company still persists, then probably the Labour Department has to be involved