Manager is forcing me to take PTO during clients holiday.

Hi Everyone, So one of my friend is in weird situation.

She works with a company ABC corp(alias) and has a client XYZ inc(alias). Since XYZ inc has vacation from 28th to 6th and she won't have any work. So her manager from ABC corp is forcing her to take leave during this period.

Now she only get like 24 days off. If she will spend her earned leave like this she will only have like 9-10 days off for the time when she will really need it.

Is this really a norm in service based company. Have you guys faced similar situation. How did you resolve this with manager.