Prefix delegations when PD is not enabled in ISC DHCPv6

[staticznld]

When looking in "Services - ISC DHCPv6 - Leases - Delegated Prefixes", I noticed that a prefix had been delegated.
My LAN interface is tracking the WAN interface with prefix ID "AAAA", with manual configuration turned off.

When checking /var/log/dhcpd/latest.log, I saw the delegated prefix as shown below:

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<190>1 2026-02-05T05:37:11+01:00 firewall.redacted.com dhcpd 71898 - [meta sequenceId="2"] Reply NA: address 2a02:REDA:CTED:aaaa::1245 to client with duid 00:02:00:00:ab:11:1c:2f:ae:81:d3:02:e2:c3 iaid= 146797512 valid for 7200 seconds
<190>1 2026-02-05T05:37:11+01:00 firewall.redacted.com dhcpd 71898 - [meta sequenceId="3"] Reply PD: address 2a02:REDA:CTED:ff00::/60 to client with duid 00:02:00:00:ab:11:1c:2f:ae:81:d3:02:e2:c3 iaid = 146797512 valid for 7200 seconds
How is it possible that a prefix is delegated when all related options are turned off?
The device requesting the prefix is a hardware Globalping probe.