4TB T7 Shield Stopped Mounting

Unfortunately if First Aid is unable to repair those errors (warnings can usually be ignored) even after several attempts, then there is nothing else you can do to repair the volume since there are currently no third party utilities available which can repair an APFS volume (Disk Warrior is working on such support, but it will likely be some time before it is released with the ability to repair APFS volumes....they would be the only third party utility I would trust or pay for to repair a file system on a Mac). You can try using data recovery software such as Stellar Data Recovery to attempt to recover the files.

FYI, if you have critical files you don't want to lose, then you need to make sure you back them up. The more important the data, the more backup copies you should have. Apple includes Time Machine backup software with macOS, so there is no reason not to have a good backup. TM can even be configured to back up external drives.

It is also possible that the part of the drive that Disk Utility is trying to repair is actually a failure on that part of the drive. The fact that it will not mount would indicate that the damage is in a critical area. So, it could be possible that the drive has failed at that location that is trying to be accessed.

The other possibility is that the firmware in the SSD has been a bit over zealous (or has a bug) in its internal attempts to keep the drive optimized and wiped that region. The error "error: (oid 0x403f25) om: bt: found zeroed-out block" could be a likely indicator that that may be the case. I have not heard any wide spread issues of this on Samsung devices but has occurred on other manufacturers SSDs.

One note is that you will need a second drive large enough to copy all the data that was on that drive. Recovery on SSDs can be questionable since depending on what actually happened, the firmware on the SSD could be quite happily be zeroing out the files (need to be done before a location can be written to since unlike HDDs, you cannot simply overwrite an SSD location), so recovery could be limited.

And to re-iterate what @HWTech mentioned, any critical data needs a backup and in a business scenario multiple backups on different devices with at least one backup offsite.