[Bug] : hcloud_server firewall_ids removed only when set to empty array

[nomorepanic]

What happened?

When an hcloud_server resource has firewall_ids set, and firewall_ids is later removed no changes are made.

Oddly, when firewall_ids is set to an empty array, firewalls are detached.

Ran with hcloud v1.48.1 on tofu 1.8.1

What did you expect to happen?

Removing the firewall_ids field should detach firewalls from the server.

Please provide a minimal working example

Example:

hcloud_server "myserver" {
   ....
   firewall_ids = [myfirewall.id]
}

Plan & apply, then remove firewall_ids:

hcloud_server "myserver" {
   ....
}

applywill find no differences.