Since you chose to manually configure a static IP address on your Pi-hole machine, you should be aware that this may shut down access to your Pi-hole if your ISP would change your public IPv6 prefix (2000::/3 range).
In such an event, you'd have to manually change your Pi-hole's IPv6 address to reflect that new prefix.
If your ISP would routinely assign new IPv6 prefixes, it may be worth considering to Use IPv6 ULA addresses for Pi-hole.