Your trading day resets every day at 22:00 UTC. This is a fixed time: it does not shift with your local timezone, and it does not follow daylight saving changes.
The reset is the reference point your daily calculations are measured against, most importantly your daily drawdown limit. Each time the clock hits 22:00 UTC, a fresh trading day begins and your daily loss allowance resets to full.
Worked example. Say your daily drawdown allowance is $500. During the day you draw down $400, leaving $100 of room. At 22:00 UTC the day resets, the $400 loss no longer counts against you, and you start the new day with the full $500 allowance again. Anything you lose after 22:00 UTC counts toward the new day, not the old one.
Because the reset is tied to a fixed UTC time, plan your open positions around 22:00 UTC so you always know which trading day your results fall into.