100% was Northland Mall
https://dailyhive.com/vancouver/nort...us-hbo-filming
Episode was good for backstory I guess, but it's hard to keep the momentum going with the main narrative when there are two 100% flashback episodes out of a total of nine episodes, one of which is for a pair of characters who don't appear elsewhere.
Personally, I like the technique where they intersperse present time with flashbacks here and there to fill in the holes. That way you can keep the momentum going.