The match ended with a 4-0 loss for Spurs, with Harry Kane scoring and missing a penalty kick against his former club.
Konrad Laimer and young players Lennart Karl and Jonah Kusi-Asare also scored for Bayern.
Frank said, "I think we played a very good Bayern team that performed well tonight. We didn't match their level, and we lacked energy, which made it difficult for us to compete."
He emphasized that his players were not lacking in motivation, pointing out that they had shown high energy in previous matches against Arsenal and Newcastle.
Frank believes that this game will be a valuable learning experience for his team, as they face a top-level opponent who is competing for the Champions League title.
He added, "We'll review the game calmly and make adjustments. We learn every day on the training pitch and from every match. We're not yet at our best, but we'll work towards improving our consistency."