@OldTreeCreeper Yes, The enemies are actually in the game, but with incomplete data (e.g. name or currently selected legend missing) The game waits for the rest of the data until they timeout. Some do make it in the match eventually, some during the buying phase, some even during the 1st round, just like in my experience below.
I had an Arena match where both us and the enemy team were missing a squad member. It felt fair, until their third came out of nowhere just as we were about to win the first 2v2 round and shot us in the back with fresh weapons from the care package that dropped away from the battle area.
Also, had a very defective reconnect, after my connection threw me out of an Arena match I got put in the middle of a BR, somewhere at the end of round 1, with 10 teams left, one squadmate dead and about to expire and the other one downed at hundreds of meters away.