Talking about Bayern Munich in the Bundesliga, Thomas Tuchel's squad is 10 points behind Leverkusen. even though there are still 10 matches remaining in the Bundesliga, it seems difficult for Bayern to reduce the point difference if Leverkusen continues to win their matches. which means, the probability of Bayern Munich retaining its title in the Domestic League is quite doubtful. even if Bayern competes fiercely again in their domestic league, that means Leverkusen has lost several of their matches in the Bundesliga. But what we are discussing in this post is not how Bayern is in the Bundesliga, but how Bayern Munich is in the Champions League.
Ten points are too big difference and if we also take into account the domination of Leverkusen in Bundesliga, this season in domestic league is already completed for Bayern Munich. Completed in term that they are no longer be able to compete for the league title with Leverkusen. With pride of a biggest and most successful club in Germany and Bundesliga, Bayern Munich will not let themselves losing many matches in coming months but to win Bundesliga, they have no chance.
As you said, Bayern Munich seems to be more focused on the Champions League. however, this does not mean that Tuchel will not maximize his squad in domestic competitions, but because there is still hope in the Champions League, Tuchel will prioritize his team's squad in this competition, especially when playing against Lazio. playing at the Allianz Arena in front of their own Die Rotten fans, the Bayern Munich squad will play hard to win the match against Lazio.
Champions League will be their last hope and at least they still have chance there. Beating Lazio and have quarter finals, that looks not a bad scenario for Bayern Munich. When coming to quarter finals, no reason to stop them fighting for semi finals and the final match. Now they will have to fully focus on a match with Lazio as it is their very last chance to avoid a failed season.