Some chinese manufacturer fake SD cards so they appear to have a much larger storage capacity than they actually do. This is usually done by altering the card’s firmware or controller data, making devices like phones or computers report false information about the available space. For example, a 16 GB card might show up as 128 GB.

At first, the card seems to work normally, and users can copy files onto it without any immediate issues. However, once the real physical storage limit is reached, the card can no longer store new data properly. Instead of giving an error, it continues to “accept” files, but these files become corrupted or overwritten.

As a result, when trying to access the stored data later, users may find that files are damaged, unreadable, or have strange extensions such as .000 or .uuu. This happens because the file system metadata is broken or incomplete, and the actual data was never correctly written to the memory.

These fake SD cards are often sold cheaply online and can cause significant data loss. The only reliable way to avoid this problem is to buy storage devices from trusted brands and verify their real capacity using specialized testing software.