There's no reason for Madrid to underestimate Bayern
They have always been one of the most dominant team in the UCL in recent years so caution would be employed while playing them no matter their form.
Madrid can be considered a favored child in UCL
No matter their form
They always are the likeliest to win the trophy and who ever manages to win them has already won the UCL.
Real Madrid will never underestimate its arch rival in the Champions League even though in recent years it has not met Bayern Munich, but now Real Madrid will be reunited with Bayern Munich in the semifinals and this will be a big match for both of them, whichever club they face. Real Madrid will definitely feel the pressure, as well as Real Madrid, which is not taking its opponents in this semifinal easy because their opponents have also fought hard to reach this round. Even though Bayern Munich appear less consistent in the domestic league, when they are in the Champions League, Bayern Munich is still the second favorite after Real Madrid.
Yes, they have won the Champions League title so for now they have the same chance of getting the title even though most people choose Real Madrid, including myself. But Bayern Munich also remains an enemy that Real Madrid is quite wary of so we'll see what will happen what happens between them later I only wish the best for Real Madrid, it remains my favorite club in the Champions League.