Can't delete devices that don’t exist anymore from Network table

The issue I am facing:
I purchased a few smart-plug devices that I tried to install, they obviously took a DHCP IP from the router. Unfortunately they did not work with HomeKit and I decided to return them to Amazon.
Their MAC, IP and Name, etc. records were added to the Network Table.

When I delete these lines, they keep reappearing.
I even flushed the Network Table, restarted the DNS, rebooted the system, but these devices keep showing up after a few minutes again and again and again.

I wish I would understand from where is this information coming back to the table if the devices are at Amazon??? I think it is some kind of bug.
I addressed this question in the Help group, thinking that some developers might respond, but there was no answer.
I am using pi-alert which is getting the information from the Pi-Hole Network Table, and I keep getting these ghost devices back as new devices.

Please help

The network table is partially populated from the neigh tables on the Pi. This command will show the contents:

ip neigh

So I guess with this command I can delete entries directly in the neigh tables? I will look into the syntax of deleting entries from this table

pi@ph5b:~ $ ip neighbour help
Usage: ip neigh { add | del | change | replace }
                { ADDR [ lladdr LLADDR ] [ nud STATE ] | proxy ADDR } [ dev DEV ]
                [ router ] [ extern_learn ] [ protocol PROTO ]

        ip neigh { show | flush } [ proxy ] [ to PREFIX ] [ dev DEV ] [ nud STATE ]
                                  [ vrf NAME ]
        ip neigh get { ADDR | proxy ADDR } dev DEV

STATE := { permanent | noarp | stale | reachable | none |
           incomplete | delay | probe | failed }

EDIT: But they get repopulated in ARP cache/ip neighbour as soon as something connects with the Pi-hole host.

Your system will update its neighbourhood tables as soon as it gets aware of a new on-link node.

For a reappearing entry in Pi-hole's network overview, is there a matching entry in ip neigh as well?

If so, that would suggest that the respective device would still be connected - it may just have a wrong label in Pi-hole's network overview.