After sustained writes, the drives file system becomes corrupted and your data is gone
A fair number of users of SanDisk Extreme portable SSDs, especially the 2TB and 4TB models of the Extreme V2 and Extreme Pro V2 are experiencing catastrophic data loss. It appears that after sustained long writes, the file system on the drive becomes corrupted and all data is lost. In some cases users have been able to use data recovery tools to recover at least some of their files, but many have not been able to restore anything successfully.
Most of the complaints concern the SanDisk SSD Extreme 4TB and Pro variant, for which SanDisk will be releasing a firmware update to address the issue. There is currently no news for owners of the 2TB model who have lost their data. Unfortunately no timeline has been provided for the release of the firmware update for the 4TB model nor details on what is actually being fixed. SanDisk has also not released any official refund policy for users who no longer want to use these drives.
If you have one, you should definitely back up everything on it to another location as soon as possible.