special character e, o, i, etc.
Until recently, I could hold down a key for a long time, for example, a vowel like e, o or i, and then I would get the option to add a special character, for example, a trema. This feature is unfortunately disabled, I don't know how this can be done. Who knows how I can turn this back on? I have a relatively new MacBook Pro.
MacBook Pro 13″, macOS 11.6