The trailing loss limit (also called the maximum drawdown) on a Spark funded account is $1,500 below your highest-ever closed-balance high-water mark, the same mechanic that applied during your Spark Evaluation. It continues trailing for the life of the account.
The limit is recalculated once per day at the 00:30 UTC reset, using your closed balance as of that reset. It is enforced against equity, so open profit or loss counts toward a breach. See What constitutes a breach in a funded account? for what happens if this limit is breached.