Questions & Answers about Kunci itu terlepas dari tangan saya.
In this sentence, ter- gives a sense of something that happened unintentionally, unexpectedly, or by itself from the speaker’s point of view.
So:
- lepas = free, loose, released
- terlepas = became free / slipped free accidentally
That accidental nuance is very important here.
Not in the same way as a normal di- passive.
Malay di- passives usually highlight that something was done by someone, for example dibuka = was opened.
ter- often works differently: it can show that something happened unintentionally, spontaneously, or simply resulted in a certain state. So terlepas is better understood as accidentally slipped free rather than a regular passive like was released.