An end-of-day drawdown, often shortened to EOD drawdown, is a loss limit that is recalculated once a day, at the firm's daily reset, using your end-of-day balance. Open profit during the day does not drag the limit up, which is the main difference from an intraday trailing drawdown.
Recalculation and enforcement are two different things. The limit only moves at the reset, but at most firms it is enforced all day: if your balance, including open trades, touches the current limit at any point, the account is closed. Topstep, for example, states that hitting the maximum loss limit at any point during the day, including on unrealized profit and loss, liquidates the account immediately.
The reset time and the reference point vary. Many futures firms reset around 5pm Eastern and use the closing balance; others measure against the higher of balance or equity at the reset. Two plans with the same dollar limit can therefore behave differently.
The common trap is reading EOD as permission to dip below the limit and recover before the close. It is not. EOD helps you because a winning trade that gives back its profit before the close does not raise your floor. Check the reset time and the breach rule on the firm's rules page before you trade. Prop trading can cost you every fee you pay.