This is all too familiar...
I am a recent retiree from a tech megacorp that instituted an "unlimited" PTO policy not long after I started working for them.
My boss said it was a good thing, as it meant that a couple of us new guys in his group could get a bit more vacation than we would have been entitled to (2 weeks) under the guaranteed entitlement plan. I was a senior engineer and had previously been entitled to 5 weeks leave at my last employer, so I regarded this as a welcome change.
That boss was laid off not long after the policy change, and my next manager announced that he interpreted the new "unlimited" PTO policy to mean "undefined" and that he consequently had discretion to dole out time off in accordance with the old guidelines, which meant I was back to 2 weeks per year. I did manage to squeeze out a bit more holidays than those 2 weeks per year but it was always with a bit of tension and it was obvious that my boss thought he was doing me a huge favor to allow it.
Of course the reason for doing so was to eliminate the financial liability of having to pay for accumulated time off when people left the company. The company also at the same time got rid of paying out 401k matching money on every check, instead making a one time payment in the next fiscal year only to those employees who were on the payroll post December 15th. This was also proclaimed as a benefit because they increased the matching percentage by one percent, but of course it was a huge "Fuck You" to the employees who left voluntarily or were laid off any time between Jan 1st and December 15th.
Extremely glad to be out of there, the most employee-unfriendly outfit I have ever worked for.
PS I made sure my last official day of employment was December 16th, and took the last week and a bit off as PTO...