Question about Red Card during the first leg of CL...

[Ristiina FC]

During the first leg, Boukris was sent-off during the game.
For the second leg, today, i see him in the line-up of my opponent.

Why ?

Is this line-up is definitive or is it the last one used in championship or cup for exemple ?

And what's happen if my opponent don't change this player ?

[Sinany03]

What you see on your screen is the squad they currently have (I’m not sure how fast that is updated when they change their squad). If they take that player off anytime between matches, you will see that change, too. If they keep him on the squad, he will be replaced by an available player at the time of the match that player is suspended.