DHCPv6 prefix delegation `sla-id` limited to 128

The sla-id parameter of DHCPv6 prefix delegations is limited to 128.
While this is enough to use all /64 subnets of a /57 prefix, with a /56 prefix that is no longer sufficient. Is there an reason for this low limit? May I open a Phabricator ticket for this?
(I’m currently using VyOS 1.4-rolling-202205200217)

It’s clearly a bug, thanks. Opened ⚓ T4447 DHCPv6 prefix delegation `sla-id` limited to 128