Company keeping my vacation days

I have worked for a very large company in Ohio for 20 years. We accrue vacation days at a set rate. In the past, towards the end of the year, if an employee has any vacation (PTO) time we have not taken, we could turn it back in to be 'bought back' by the company at our regular rate, or allowed to carry over to the next year. This year they have decided that they will no longer buy back the vacation time at full face value, but will only pay you at a rate of 75% of your normal pay for the hours you turn in. They also have decided to cap how many hours you can turn back in, limiting it to 100 hours. Now this company doesn't allow vacation between Nov. 20th and January 1st each year, so many people are being forced to 'forfeit' their earned vacation time or receive only a partial payment. They are also taking 30% out of the 75% you receive and say it is for taxes, so in actuality you are only getting paid 45%. Is this legal?