Many players from Real Madrid are currently injured, which makes all of Real Madrid's performance not good. Usually, Real Madrid is able to lead or at least compete in the first and second positions, but currently the point gap between Real Madrid and Barcelona is very wide, so Real Madrid is more choosing to stay calm and not really chase the first position anymore because it was impossible to catch.
Which players do you mean? From what I know, there is 1 injured player now (Ferland Mendy).
So, it is untrue that many players of Real Madrid are injured. Check again their squad information:
https://www.transfermarkt.com/real-madrid/kader/verein/418They played very well in the current El Classico. So, they have no problem with their performance.
For the previous matches in La Liga, they didn't play well constantly because Benzema often gets injured. But now Benzema is available, Real Madrid can have a chance to chase Barcelona again in 1st place.