When a STA roams from API to AP2 at Layer 2, AP2 notifies its neighbors...

When a STA roams from AP1 to AP2 at Layer 2, AP2 notifies its neighbors of the MAC address learned from this STA. The MAC address is not encapsulated in a tunnel and sent to AP1 for forwarding. Instead, AP1 deletes the MAC address entry of the STA and releases the IP address lease.

References: https://support.huawei.com/enterprise/en/doc/EDOC1100058940/8a8f1c9b/layer-2-roaming