Hi there rfflcm,
If Apple Translate isn't working as expected for you on your iPhone, let's start by making sure it's updated to the latest iOS version, which is iOS 16.0.2. You can check the installed version by going to Settings > General > About > Software Version. For more information about updating iPhone, have a look at this support article: Update your iPhone or iPad - Apple Support
If you open the Translate app and try to translate the text directly from there instead of in a third-party app, like WhatsApp, does the issue persist? You'll want to be sure you're following these steps:
Translate text or your voice
1. Tap Translation, select the languages to translate between, then do any of the following:
Note: See Choose the languages you want to translate between.
- Tap “Enter text,” type a phrase, then tap Go.
- Tap , then say a phrase.
2. When the translation is shown, do any of the following:
- Play the audio translation: Tap .
- Save the translation as a favorite: Tap .
- Look up a word in the dictionary: Tap , then tap a word to see its definition.
- Show the translation to someone else: Tap .
You'll find this information here: Translate text, voice, and conversations on iPhone - Apple Support
Take care.