next-intl Dot Notation Error Fix

Problem

next-intl throws INVALID_KEY: Namespace keys can not contain the character "." when translation JSON files use dots as literal characters in key names instead of for object nesting.

Context / Trigger Conditions

Exact error message:

INVALID_KEY: Namespace keys can not contain the character "." as this is used to
express nesting. Please remove it or replace it with another character.

Invalid keys: email.notification.booking (at unsubscribe.categories), ...