Federal employees can't take vacations during a furlough, unless your name is Jared or Ivanka

[onenote]

5. If you read the OMB Directive linked in the article, you'll see that the headline is hyperbole

There are a number of categories of federal employees who are not subject to being furloughed and who also are not subject to leave policies, including political appointees.

Whether such employees should voluntarily forego vacations during a shutdown is a different question. Moreover, a number of government agencies were previously funded and thus remain operational. Employees of those agencies can take vacations and I think that's entirely appropriate.

https://www.opm.gov/policy-data-oversight/pay-leave/furlough-guidance/guidance-for-shutdown-furloughs.pdf