I was able to verify this.
*If you try and contribute ("Put") into the cooking pot between during the EST hours you get the Put button but it produces a time mismatch error when you press it.
*If I tried during the correct time in my timezone the button would not work at all.
As someone who has done some web development it looked to me like the server expected EST but the application code was looking at the local computer of the user and even if it was the correct time EST it would show a mismatch.
I verified this on the last day: At approx 8:00 EST I tried and got the error. Then I changed my local computer time to use EST and it actually allowed me to complete the function.
In chat I checked with others and only people living in EST were able to make it work correctly.
People spent money to participate and likely some had limited functionality if any at all. I hope that STK adjusts the situation correctly.
Screens are attached.