We're deprecating Node.Capabilities (a []string) in favor of the more expressive Node.CapMap (a map from those same strings, but to zero or more values associated with that capability). (see https://tailscale.com/blog/acl-grants)

One place this shows up is tailscale status --json which has both forms.

We're going to remove the old Capabilities []string in 6 months or so. In the meantime the two will mirror each other, with the older form just lacking arguments.

/cc @maisem