When spectacting any game, very frequently past mid game (10+ minutes) a 'locked' flex slot for one or both teams will show an item that someone else (often from another player) has purchased in that slot. The game will display this same item for all players in the same slot. Sometimes from an enemy team member who DOES have that flex slot unlocked. Purely visual bug afaik.
Widely known bug on twitch, just making sure there's a post about it
Widely known bug on twitch, just making sure there's a post about it