Joselu rarely found his place in Real Madrid's starting XI, but Real Madrid never wanted to lose this player from their club. The big reason behind this is that if any player in their original XI is injured, then Real Madrid will close their eyes and give this player a chance in his place. Joselu may stay at Real Madrid for one more season for sure, but there is another thing here that he will not get a place in the regular eleven next season, he can be seen on the field as a changed player. With Mbappe joining Real Madrid, there is no doubt he will play regularly, so Joselu may have to spend next season on the bench.
His quality is not qualified to be a starting player in the Real Madrid squad because he is not a world-class player, he is just there in the team to come in as a super sub whenever they are in need of goal or when any of their wingers get injured. I am expecting him to leave Madrid this time because Mbappe just joined them and Ancelotti will definitely use both Rodrygo, Vinicius, and Mbappe in the front line, he(Joselo) will not have enough playing time in the team
Obviously, it will be quite better for him to leave Madrid and join another suitable club, because with the presence of these trios, Neymar, Vinicius and Rodrigo in the front line of Madrid, he will definitely get overshadowed by the performance of these three incredible players and would hard see match to play, However it is an individual choice to make as well Real Madrid decision to keep in the club.