Android devices cannot be directly connected after using the exit node, but can only use relays

Android
1

Exit Node: Debian 11 / Tailscale 1.38.2
Android Device: Pixel 3 XL / Tailscale 1.42.0
iOS Device: iPhone 11 / Tailscale 1.42.0
They all have ipv6 addresses.

When the exit node is not used on the Android device, the Android device can be directly connected to the exit node. When the exit node is selected, it cannot be directly connected to the exit node, but can only be connected through a relay.

Another iOS device in the same network environment as the Android device does not have this problem, and can be directly connected regardless of whether an exit node is used or not. Why is this?