It's interesting that some people get stressed-out and anxious while on vacation. This phenomenon is due to the fact that while you are anxious and stressed, your body is in the fight or flight mode, where you are revved-up to either fight or work through the stress (ie staying up all night to meet project deadlines) or running away or avoiding the stress (ie actively getting out of projects with difficult coworkers). So in essense, the fight or flight response is your body's solution to dealing with stress and anxiety, as your body is gearing-up to meet the challenges of the stressors.
However, when you are on vacation and the stressors of work and people are gone, somebody forgot to tell your body that you are on vacation, and it therefore continues to function in the fight or flight response, especially if you had been exposed to chronic stressors. It is as if your body gets used to being in this ramped-up state, and does not know when to stop, even when the chronic stressors are removed.
So the reason you get stressed-out and anxious while on vacation is that you need to help your body cool down and reduce its activity, as it still thinks you are embattled with multiple stressors.
You have to tell your body it is on vacation, and you need to perform relaxation techniques to calm down your body. If you find your thoughts are contributing to your anxiety, then these relaxation techniques can also help to calm those down too. Here is a link detailing the various relaxation techniques: https://anxietyboss.com/anxiety-treatments/relaxation-strategies/