After updating my macOS to 11.3.1 from 11.3, a directory named `Relocated Items` appeared on my desktop.
A document in that directory explained a bit about what's going on. I will attach the text of the document below.

so I viewed a diff between `/etc/group` and `~/Desktop/.../group.system_default` and saw that
the line containing `_trustd:*:282:_trustd` exists in `group.system_default` but not in `/etc/group`.
Another odd thing I realized is the 'Date modified' on the file on `group.system_default` is 1. Jan 2020. This computer and the install are both from 2021.

Can somebody explain what is going on? I am not sure which of the files came with the macos-update and which I suposedly modified in the previous version.
I also don't understand what `_trustd:*:282:_trustd` means.

**Document in Relocated Items Directory**

> 
> During the last macOS upgrade or file migration, some of your files couldn’t be moved to their
> new locations. This folder contains these files.
> 
> 
> **Configuration files**  
> 
> These configuration files were modified or customised by you, by another user or by an app.
> The modifications may be incompatible with the recent macOS upgrade. The modified files are
> in the Configuration folder, organised in subfolders named after their original locations.
> 
> 
> To restore any of the custom configurations, compare your modifications with the configuration
> changes made during the macOS upgrade and combine them when possible.
> 
> 
> Configuration files with the suffix "system\_default" were edited or customised but the changes
> were allowed to remain installed. The system\_default version of the file is provided to
> demonstrate what the Apple-supplied version of this file would look like.
> It is recommended you compare the two and evaluate whether you wish to integrate any changes
> Apple may have made to the default version.
> 
> 
>