Interesting theory about the speakers but as SD cards and flash drives do not store data magnetically they are generally not affected by magnetic fields especially the relatively weak ones in speakers. More details about this here-
https://www.machinedesign.com/blog/5-myths-surrounding-usb-flash-drives
In my experience data corruption in decent brand SD cards is rare and is more related to issues with the camera such as firmware that needs updating or a card that hasn’t been reformatted in a while or corruption on the computer’s internal or attached storage.
Noah
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