Employer Got Bought Out. Expiring Our Pto

Location: Chicago, IL

Theoretically...

My employer recently got bought out by a large institution. Our old PTO policy had us accumulating 1.5 days of PTO per month. Our work days were considered 7.5 hours. This all lines up with our employee handbook.

My new company has decided to not pay us out and, instead, roll over our PTO onto their policy. We cannot be part of their PTO policy until we use all our old balance. They have also implemented a threshold that states after one year - any PTO over 21 days will expire. Then the year after, if any PTO remains. All will expire.

There has also been some confusion on their end regarding what is considered "one day of PTO." Our old policy states we accumulate 1.5 days a month.(15 hours a month at 7.5 hours). If they make us put in 8 hour work days instead of 7.5 hour work days we are effectively losing PTO during that convergence.

Example PTO convergence:
I have 25 days of PTO stored from my old job - 187.5 hours at 7.5 hours a day.
New policy with 8 hour days will reduce my days from 25 to 23.4375 because 187.5/8=23.4375.

Expiring example:

I have 25 days of PTO at the day of acquisition. I hold onto those days until December 2026 and don't use any. On Jan 1st, I will be reduced to 21 max days.

I hold onto the 21 days until December 2027. On Jan 1st, I will have 0 days of PTO.

Few question:
Can they expire my days?
Can they reduce the amount of PTO I carry over because of the 7.5/8 hour swap?