Greetings
I don't know if this is a new feature with the recent update, but I couldn't find anything referencing what happened to me
While playing the Heroic Strike playlist, I was transitioned into a Blind Well level 3 session. As you can see in the video, I never left the playlist.
I was actually kind of happy that it happened cause I still needed the well this week. If this is by design, it still needs some work. If not, then I give you video evidence that it happened
Peace!
You were loaded into an ongoing strike (The Corrupted) that your two teammates (That you got matched with post-Pyramidion) were currently active on. Their third player left which opened a spot for you. Since they had decided to backtrack from spawn at the beginning of the strike and load into the Well, this resulted in you spawning in at the Well with them.