They will not highlight these during recruitment and onboarding: that client territory holidays are mandatory off days. If you are a regular employee, they can be deducted from your accrued PTOs. Otherwise, salary deduction.
Note that there are only 20 PTOs. Come regularization, they will tell you it's meant to be used for 10 vacation leaves and 10 sick leaves. With about 7-8 client territory holidays to be taken off your entitlement, then do the math. You are only left with 2 vacation days you can use on your own discretion. None of these are written in the contract, not even in their company's handbook. Now 20 PTOs doesnt even sound like a benefit at all, right? It's like a favor from them they want full control of.