Basically, you get the Falcon Wings in patch 2.4.1 via a Mysterious Chest in Act 4 Gardens of Hope 1st tier. It’s not exclusive to season 6, nor do you need to resort to having a menagerist pet goblin.
I’ll be going over what YouTuber Rhykker talks about in his guide here.
The pursuit for the Falcon Wings is entirely luck based, and it’s based on pure chance that you’ll come across the Mysterious Chest. The chest itself apparently drops the wings 100% of the time, however. Rhykker was lucky and got it on his second runthrough (about 7 minutes into the video).
Rhykker recommends using a “Speedrun” character build. The Mysterious Chest can potentially appear anywhere on the map, so it’s all about navigating the area as fast as possible. The only difference between the Mysterious Chest and any other regular Chest is the name. The Mysterious Chest will not appear on your mini-map, so you have to look around the location for yourself to find it. If it doesn’t appear in the Gardens of Hope on that particular run, leave game and come back to try again.
The game difficulty apparently doesn’t affect the spawn rate. So happy hunting!