It didn't even start now, if you noticed or maybe have been watching Real Madrid games you will understand that it happened even from Ancelotti's era. Just towards when the season was to be wrapped up that Rodrygo started seeing more of the bench than previous. He actually declined in form of the truth and Ancelotti most of the time at that few games before the end of the season, dropped him even when he was not injured. Alonso only made it clear that he was not part of his plans after he publicly asked Guler not to leave that he is in his plans.
Seriously. The new coach, which is Xabi Alonso, has made it clear that Rodrygo is not one of the players that he is planning to use next coming season, and as you said earlier, even before, Ancelotti was not even using him that much. Due to his performance, I think the player is not in good performance, and since Xabi Alonso wants everything to go smoothly in his team, he doesn’t want things to go another way for him. That is why he is arranging the players that can make his strategies go well for him ahead of next season.
I think Xabi Alonso wants to restore Real Madrid's performance and confidence for the next coming season. We know how Real Madrid struggled last season, and I think Alonso doesn’t want the same thing to happen during his time. We should be expecting great performance from Xabi Alonso. I think he has started making his arrangements from now, which is good.