If I understand the rules correctly, whenever a player receives red card, he is suspended for the next match. The same is true for 3 yellow cards. See, for example, here.
I would like to know what happens in the situation illustrated in the following example.
During the match in U-21 Euro qualifying play-offs Slovak midfielder Ondrej Duda was sent-off, see here or here. As of this moment, this was his last match for national team, see for example his profile on soccerway.
These are two different competitions, but both of them are organized by UEFA. I wonder whether he should be suspended in the senior team 's game or whether the suspensions are counted separately for senior and junior events. (Or, more generally, for various competitions.)
Even if the suspensions are not considered separately, another factor here might be that the U-21 qualifying tournament is already completed.
TL;DR: If a player receives a suspension in U-21 competition, can he still play for senior's team? Is there a difference if the junior competition, where the player received suspension, is already completed?