smartphone: protection of the Android debug bridge that is connected to the Internet

Basically, it has a powerful debugging service without listening authentication on the TCP port exposed to the Internet.

Do not expose it to the internet.

Do not limit yourself to putting it on the internet. Put it behind a firewall (I suppose that the NAT of the simple home router would also count) and configure VPN (or ssh tunnel or similar) so that only authorized people can connect.

Put it behind a firewall

The previous option is preferred, but this may also be acceptable to you (but it is vulnerable to man attacks in the middle).

a) Configure the firewall to allow only specific IP connections

b) Use the port that hits