There is a great discussion with solution on how to stop flooding with ptr requests here. However, in my setup I don't use pi-hole as the DHCP server, so the fix won't work for me.
Any ideas how to tackle this? My DHCP server is a fritzbox (which the Velop bridges)
Check the Velop settings to see if you can specify manual settings, and manually set the DNS server to be the router instead of the Pi-hole. When I wrote that workaround I don't think you could, so using the technique listed was an alternative way of achieving it.
I believe Pi-hole v6 has the ability to ignore clients in the Query Log so that will make the problem, of not being able to avoid the noise they make, go away.
Edit – Advanced Settings > Internet Settings in the Velop according to a guide.