Pihole doesn't block anything on my Xiaomi Mi A3 using Chrome

[deHakkelaar]

That second IPv6 address is probably not Pi-hole ?

[fixed] Pi-Hole newbie with DNS issues

If your ISP doesnt provide you with IPv6 support, its of little use to have your LAN support IPv6 as well. It only complicates matters. The debugger failing to resolve via public DNS is expected if no IPv6 support upstream. I would disable everything IPv6 related on router and Pi-hole.