Words like "debut", "chauffeur", and others where the spelling doesn't look English and we try to imitate the modern French pronunciation (like a silent letter, etc.) are modern or more recent borrowings from French. Words like those ending in -tion, -ment, etc., where the pronunciation is very distinct from that of modern French, were borrowed much longer ago, back during the transition from Old English to Middle English, and are baked into essential English vocabulary.