败坏 (bài huài): to ruin; to corrupt; to undermine

After he became manager, he started embezzling and taking bribes; this behavior ruined the company's reputation.

After that restaurant was exposed for using expired ingredients, it ruined the reputation it had built up over many years overnight.

He injured someone while driving drunk; it not only ruined his personal image but also cost him his job.

A parent maliciously insulted the teacher in the group chat; this behavior ruined the atmosphere of the class group.

That internet celebrity fabricated rumors for traffic and ruined the online environment, and was eventually banned by the platform.