The tag wiki for data-explorer says:
The Data Explorer, located at data.stackexchange.com, allows you to create and run queries against copies of the databases of popular StackExchange sites to investigate trends or satisfy your curiosity.
So there's a link to the FAQ, but it seems to imply that
data.stackexchange.com is the place to ask questions about Data Explorer (I can't find any questions about DE there, though). By contrast, Where can you discuss or ask for comments on a data explorer query? says questions are asked here. Which one is it?