Why English spelling and English pronunciation stopped matching around 1600

Between the 1400s and 1600s, English speakers gradually shifted how they pronounced every long vowel, so that, for instance, 'bite' stopped rhyming with 'beet', while spelling had already begun to standardize around the older pronunciations. The result, known as the Great Vowel Shift, is a big reason English spelling looks so disconnected from how words actually sound today.

— Standard historical linguistics accounts, Great Vowel Shift — 15th-17th century sound change