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4 days agoShredding might not work the way you expect on a SD card.
The memory cells in a SD Card can only handle a limited amount of write operations. A SD card typically has more cells than needed, so the controller can switch through different cells to improve the overall lifetime of the card. Which means you can’t be sure which cells gets rewritten when shredding, so the data you want to be gone, could still be readable.
If you want to secure your data, use strong encryption. Because what you gonna do, if you can’t destroy or get rid of the SD card?
I don’t know how MacOS time machine works exactly, but if it constantly writes on the SD card you should consider changing to an external SSD or HDD. The best backup isn’t helpful if your backup medium dies.