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f3 is a suite of tools to identify fake flash drives, start with;
sudo apt install -y f3

srj@srj-pi:~ $ lsblk -f
NAME        FSTYPE FSVER LABEL  UUID                                 FSAVAIL FSUSE% MOUNTPOINTS
sda
└─sda1      ext2   1.0   Thumby 51b29888-e4cf-422c-a3b7-294d8bfbbf4d
mmcblk0
├─mmcblk0p1 vfat   FAT32 bootfs 4EF5-6F55                             453.9M    11% /boot/firmware
└─mmcblk0p2 ext4   1.0   rootfs ce208fd3-38a8-424a-87a2-cd44114eb820   10.9G    17% /
 
srj@srj-pi:~ $ sudo f3probe /dev/sda
F3 probe 8.0
Copyright (C) 2010 Digirati Internet LTDA.
This is free software; see the source for copying conditions.
 
WARNING: Probing normally takes from a few seconds to 15 minutes, but
         it can take longer. Please be patient.
 
Probe finished, recovering blocks... Done
 
Good news: The device `/dev/sda' is the real thing
 
Device geometry:
                 *Usable* size: 57.81 GB (121241601 blocks)
                Announced size: 57.81 GB (121241601 blocks)
                        Module: 64.00 GB (2^36 Bytes)
        Approximate cache size: 0.00 Byte (0 blocks), need-reset=no
           Physical block size: 512.00 Byte (2^9 Bytes)
 
Probe time: 24'48"

f3 includes 5 applications, f3probe(1), f3brew(1), f3fix(1), f3read(1), f3write(1)

• f3probe - probe a block device for counterfeit flash memory
• f3brew - help developers to infer how fake drives work
• f3fix - edit the partition table of a fake flash drive
• f3write, f3read - test real flash memory capacity