Windows build number: 10.0.20150.1000
Your Distribution version: Ubuntu 18.04
Linux version 4.19.121-microsoft-WSL2-standard

Steps to reproduce

New-Item -Path $env:SystemDrive\Temp -ItemType Directory -Force
[Environment]::SetEnvironmentVariable("TMP", "$env:SystemDrive\Temp", "User")
New-ItemProperty -Path HKCU:\Environment -Name TMP -PropertyType ExpandString -Value %SystemDrive%\Temp -Force
[Environment]::SetEnvironmentVariable("TEMP", "$env:SystemDrive\Temp", "User")
New-ItemProperty -Path HKCU:\Environment -Name TEMP -PropertyType ExpandString -Value %SystemDrive%\Temp -Force
[Environment]::SetEnvironmentVariable("TMP", "$env:SystemDrive\Temp", "Machine")
New-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" -Name TMP -PropertyType ExpandString -Value %SystemDrive%\Temp -Force
[Environment]::SetEnvironmentVariable("TEMP", "$env:SystemDrive\Temp", "Machine")
New-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" -Name TEMP -PropertyType ExpandString -Value %SystemDrive%\Temp -Force
[Environment]::SetEnvironmentVariable("TMP", "$env:SystemDrive\Temp", "Process")
[Environment]::SetEnvironmentVariable("TEMP", "$env:SystemDrive\Temp", "Process")
reboot-computer

Expected behavior

ip address show eth0
4: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
link/ether 00:15:5d:cf:68:53 brd ff:ff:ff:ff:ff:ff
inet 172.27.23.53/20 brd 172.27.31.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::215:5dff:fecf:6853/64 scope link
valid_lft forever preferred_lft forever

Actual behavior

ip address show eth0
4: eth0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether 00:15:5d:cf:62:05 brd ff:ff:ff:ff:ff:ff