SInce “mgn” is the name of your Wi-Fi network, then the key requested is probably containing the password for accessing it. At least that’s the case on my system (looking for a key with the same name as my network).
The fact that the app is not named and a generic icon is presented instead of an app icon tells me that this is probably an app without a UI associated with it.
To be on the safe side, I would perform a Malwarebytes scan, in case there is something malicious requesting access to that key, but my gut feeling is telling me that this is some system service trying to read or update your Wi-Fi password.
You may want to go to the Network system settings page and re-enter your Wi-Fi credentials. That should re-write that keychain entry and update whatever system services use it. I don’t know if that will solve the problem, but it’s worth a try.
You could also try deleting that key from your keychain and then reboot. That should cause macOS to ask you for the password when it next tries to connect to your network, after which it should re-write the key.