There have been many reports of failing μSD cards.
I can think of multiple reasons.
- Poor quality card
- Card not meant for write mostly applications, and "write cycles" used up.
- Power lost while writing to card, or card ejected while writing to card
has a response from SanDisk stating that this card should not be used for continuous writing applications.
and instead recommends High Endurance cards that are designed for use with dash cams.
In this youtube video, Car Cam Central specifically recommend avoiding the SanDisk Ultra cards for use in Dash Cams, and state that SanDisk will not honor their warranty if the card is used in a dash cam.
Dash Cam 101 - Guide to SD Cards & Our Recommendations - Avoid Sandisk Ultra!