The loopA dashcam writes clips of a minute or three in sequence and, when the card is full, deletes the oldest and writes over it. Footage older than the loop is not deleted in the recoverable sense; it has been overwritten, and no bench can bring it back. What can be had is everything inside the loop, including clips the camera deleted but had not yet written over, and the clip that was being written when the camera stopped.
The event clipDashcams detect a collision from their accelerometer and move the clip into a protected folder the loop will not touch; the better ones make that folder read-only. A collision that also cut the power leaves the clip cut short, with its index never written. It is rebuilt on the image from a reference clip recorded by the same camera at the same settings, and it plays.
WearFlash wears by being written, and a loop writes a card's whole capacity every day or two. Endurance cards are built with flash rated for that and the ordinary ones are not, which is why Samsung's warranty excludes the use and Kingston steers commercial users to its industrial cards. A worn card locks itself read-only when it runs out of spare blocks, or errors on write so the camera asks for a format. Both leave the footage readable; the format does not.
Home cameras and their cloudsTapo, Ring, Reolink, Wyze, Eufy and Arlo cameras write to the card in their own folder layouts, some in ordinary MP4, some in a stream the app expects to read. The card is imaged and the clips are either copied out or rebuilt to play on their own. Where the camera also uploads to a cloud, the cloud copy is worth checking first; where it was local-only, the card is the only copy.