Quite likely, that isn't an error.
You are running that dig from the machine hosting your Pi-hole with an unscoped LLA, where some OS varieties would require a scope id.
Your lookup will likely succeed if you extend your statements by %interfacename of the network interface of the client that runs the lookup, e.g. if that client is using eth0:
dig @fe80::be24:11ff:fef2:d4e%eth0 heise.de