IPA: /ˈfɔːltˌfaɪndər/
KK: /ˈfɔltˌfaɪndər/
A person who often finds faults or criticizes others for small mistakes.
She is known as a faultfinder, always pointing out the flaws in everyone's work.
Faultfinder → It is formed from "fault" (from Old French *faulte*, meaning a defect or error) and "finder" (from Old English *findan*, meaning to discover or locate). A faultfinder is someone who discovers or points out defects or errors.
Think of someone who 'discovers' ('finder') 'defects' ('fault') in things — that's why a faultfinder is someone who points out faults.
No commonly confused words.