(This is my first time reporting wireguard issues, please kindly let me know if this is the wrong place.)
I'm on Windows 10, and had no luck enabling WireGuard tunnels with the builtin WiFi hotspot feature at the same time. When I do so the tunnel stops working, and for some reason in Task Manager I'm seeing hundreds of Mbps of outbound traffic generated on the wireguard interface (but no actual traffic to the internet). The tunnel process also takes up a full CPU core seemingly due to the generated traffic. Upon switching off the hotspot the tunnel comes back to function. I wonder if this is a known issue? I believe it's a common use case to share a VPN tunnel with devices via hotspot. This seems unrelated to the "kill-switch" feature as it happens with or without it. FWIW I also tried both Wintun and WireGuardNT backends, and the same happened with both. My environment: Windows 10 version 20H2 build 19042.1110 wireguard-windows version 0.4.2 Thanks!
