Complex sentence: Entrusted to Shido, Mayuri is raised until she reached adulthood, then placed within suspended animation in a casket until her talents are needed to suppress her human emotions, which is widely seen by her caretakers as a liability due to the nature of her powers.
Split into simpler sentences: Entrusted to Shido, Mayuri is raised until she reached adulthood, then placed within suspended animation in a casket until her talents are needed. She is raised with her human emotions suppressed, as having emotions is widely seen by her caretakers as a liability due to the nature of her powers.