Company switching up cultural policies after 6 months from initial joining

I joined a mid sized Startup in January last year, where the offer letter stated flexible working hours and unlimited leave policy, around September last year they introduced a leave and a wfh policy which was fine, now they are planning to turn it into a shift based system and everyone will need to clock in x hours and put a completely planned leave and wfh policy(no ad hoc allowed ever). Is this normal for companies to change the polices this frequently and isn't it false promising to do such practices. I mean what is next they reduce my salary to half with some weird stipulation and still I can't do anything about it?