Is it necessary for Npp to be run as administrator?

No. Except when you are editing a protected file (like something in C:\Windows\ or C:\Program Files), or when briefly performing an action like installing a plugin or Settings > Preferences > File Association, you should not need to or even usually choose to use Administrator mode.

Aside from network issues in Admin, that mode also prevents you from dragging a file from a normal Windows Explorer window into Admin-Notepad++, and there are probably other subtle downfalls to regularly using Admin mode.

If your experience is that you do need Admin to edit normal files or to use Plugin actions, then you’ve probably got a very strange configuration (ie, something is messed up in your installation). If that’s really the case, my first line of action would be to exit Notepad++ completely, rename %AppData%\Notepad++\ to %AppData%\Notepad++.bak\, and run Notepad++ not in Admin mode, which will cause Notepad++ to re-create %AppData%\Notepad++\ with your active user… so hopefully you’ll have the permissions you need, and I think your “need for Admin” should go away.

If that works, you might eventually have to manually copy contents (not the files themselves) from the %AppData%\Notepad++.bak\ hierarchy to the %AppData%\Notepad++\ hierarchy to bring back over settings, but that’s for future-you to worry about.

Network mappings are not available in elevated apps.

This raises an interesting question for me. Is it necessary for Npp to be run as administrator? For example, are there features, plugins, etc that won’t work if not in administrator mode?