There is a hidden method to share your WiFi over Ethernet in the latest Gnome.

1. Type nm-connection-editor in your terminal.
2. Add a shared network connection by pressing the Add button.
3. Choose Ethernet from the list and press Create.
4. Click IPv4 Settings in the left.
5. Choose Shared to other computers by clicking the Method drop-down menu.
6. Enter a new name like Shared WiFi LAN as the Connection name at the top
7. Select the newly created connection from wired connection.