Why does an error occur when duplicating files larger than 2 GB on Mac?

I'm assuming this occurs on the internal SSD.

Try restarting the computer to see if that makes any difference. If you still have the issue, then boot into Safe Mode to see how it behaves.

Try running Disk Utility First Aid on the hidden Container. Within Disk Utility you may need to click "View" and select "Show All Devices" before the hidden Container appears on the left pane of Disk Utility. Even if First Aid says everything is "Ok", click "Show Details" and scroll through the report to see if any unfixed errors are listed. If there are any errors, then run First Aid again until they are gone. If they cannot be repaired, then run First Aid while booted into Recovery Mode to see if the error can be repaired. If they still cannot be repaired after several attempts, then you will need perform a clean install of macOS by first erasing the disk followed by reinstalling macOS & restoring from a backup.

Do you have the same issue when you copy the folder to a different drive such as an external drive?

I recently had a problem copying a folder where macOS/Finder complained of an empty corrupted file. I was able to copy the folder without errors by using the command line. Surprisingly the "bad" file showed zero bytes on the source (external exFAT volume) although I could read the contents, but showed as 4GB when transferred to another drive using the command line. This may be an option for you as well.

The easiest method of using the command line to copy the folder would be to begin by typing the beginning part of the command "cp -Rv " making sure to have at least one space after the "v". You can omit the "v" if you don't want the verbose option.

cp  -Rv

Then use the Finder to drag & drop the source item onto the open Terminal window with the partial copy command you typed which will auto fill the correct path to the source item and should leave a trailing space afterwards.

You will need to provide the full path to the destination. You can drag & drop a folder from the Finder onto the open Terminal window to auto fill the path to that folder so you can transfer the item to within that folder.

Here is an example of what it will look like for duplicating the folder "Test Folder" located in my Documents folder so the duplicate copy has a " 2" in the name just like macOS includes when duplicating an item. You can drag & drop the source item twice, but make sure to add the double quotes and the extra text to make the duplicate a unique name. By enclosing the extra text in double quotes you can have a space or special characters in the name if desired.

cp  -pRv  /Users/hwtech/Downloads/Test\ Folder   /Users/hwtech/Downloads/Test\ Folder" 2" 

If you want to make a duplicate copy of the folder within the same folder, then here is another method you can easily use as well by deleting the trailing space after the source item and adding the following ( without the need to drag & drop a destination):

,{"<extra text to make a unique name>"}

So with the previous example would become:

cp  -pRv  /Users/hwtech/Downloads/Test\ Folder,{" 2"}

Both methods will give you a duplicate of the source folder with " 2" added to the end of the folder name so you will see these two items in the Downloads folder within the Finder:

Test Folder
Test Folder 2

You do have to be very careful when using the command line since there are no safety nets. Just a simple typographical error can cause unexpected & unintended consequences. For example, having a trailing slash character "/" after the source folder will give you a slightly different outcome than what I've shown you here.

Where are you copying it to? An external disk? What format is that?