@JLegere it’s based on the timezone that was set by their browser when they booked the call - if the browser detected CST, then that’s what time shows, not CDT. Depending on how long ago they booked the meeting that could potentially have an impact, but most likely their browser is set to the wrong time zone.
This is a reminder I had from today that shows EDT based on the recipients time zone:
There is an option when they book the meeting to correct the time zone if their browser didn’t detect the right one:
