When you reinstall Windows from a clean USB/ISO, it doesn't include some customisations which the Microsoft Store requires in order to let you download and install the "My Dell" app.
The "My Dell" app can be helpful for managing power/thermal profiles and charging customisations as well as some other things, too.
You need to set some values in the Windows registry to make Windows think it's a Dell-installed copy of Windows.
Press Win+R to open the "Run..." prompt. Type "cmd", then press CTRL+SHIFT+Enter to launch it as an administrator.