Ancelotti underestimated such a talented player. Arda Guler was not given enough opportunities in the last season. But every coach has different preferences. For example , Ancelotti gave Rodrygo a lot of chance, and Alonso did not like Rodrygo's style of play.
Arda guller has performed well in all three matches with Madrid this season. Arda Guler's rating was 8.5 + in the matches against Real Oviedo and Mallorca. He is becoming one of the most important players in Madrid's midfield. Madrid's midfield will become even stronger after Bellingham returns from injury.
Yes, Ancelotti and Xabi have different perspectives on Guler, and I think that's understandable. Ancelotti's coaching style and Xabi's are very different. Therefore, it's natural that there are slight differences in player selection. However, Xabi's current approach does appear to be improving, as Arda Guler now has a clear place in the Real Madrid starting lineup. Furthermore, his performance is clearly showing signs of improvement. However, Guler still needs to work on himself to improve his performance at Real Madrid. Last night, Guler played quite well, as evidenced by his goal against Mallorca. So, with that in mind, Guler could be a valuable asset for Real Madrid in the future.

Furthermore, Real Madrid currently sits first in La Liga, which is certainly a great start for Real Madrid. Furthermore, next week, Real Madrid will face Real Sociedad. I think this match will be very exciting to watch, as Sociedad is certainly a pretty good team and perhaps even stronger than Mallorca. So, with that in mind, I think the match against Real Madrid will be very exciting.
Image source: Google