Knowing that you could get a call, email, or text from your boss that you're expected to respond to, regardless of the day or time, can be incredibly stressful. An occasional email or text after hours for something genuinely urgent is not abnormal, but consistent out-of-hours contact is a red flag.
If no one ever uses up their allotted time off, you might feel pressured to do the same. But this leads to burnout fast. Never taking time off is unhealthy, and that is understood in a good professional enviornment.