Madrid's defense line is indeed weak compared to Dortmund if calculated by the number of goals conceded. But Madrid has a strong and fast front line. And they are all capable of scoring goals, meaning it doesn't depend on one player. Vini, Rodry, Brahim are young players who are reliable and fast. Can Dortmund's defense stop them? Bellingham, Valverde are also players who are ready on all fronts. Aurelien and Camavinga are midfield players, but are ready to play in defensive positions. I think this is something that Real Madrid has an advantage that other clubs in general don't have.
Real Madrid defense line is weak you think? I don't agree with you. I accept that Dortmund have been really successful in defense recently. Luck has also played a good role as for example PSG had so many shots hitting the post as I must have said before. However I can't still trust their defense that much honestly. For example they are way worse than Real Madrid on that when it comes to domestic league performances.
Otherwise I'm okay with watching a different champion here.
Real Madrid have been dominating the Champions League so far. It has been like 17 years since Dortmund won it the last time. It wouldn't be bad to see them putting an end to this longing.