Yes, anxiety can occur while on MDMA. Many people report feeling safer or more relaxed, but that effect is not guaranteed, and I cannot verify exact rates.
Mindset and setting matter. Underlying tension, trauma, or mistrust can make anxious moments more likely, so preparation and a calm, familiar environment help.
If you choose to use it, plan for unease: have a quiet space available, reduce noise and lights, try calming breathwork or music, and have a trusted sober supporter. Avoid mixing with other substances.
For a short overview in context, see this Q&A on anxiety during MDMA: anxiety while on MDMA. Stay safe.