Weakening

1. To reduce in intensity or effectiveness (Merriam Webster English Dictionary).
2. Becoming weaker (Vocabulary English Dictionary)

Sources:

Merriam-Webster. (2024) Merriam-Webster, Incorporated. Weaken. In Merriam-Webster.com dictionary. Retrieved from https://www.merriam-webster.com/dictionary/weaken

Vocabulary.com. (n.d.). Weakening. In Vocabulary.com Dictionary. Retrieved from https://www.vocabulary.com/dictionary/weakening