I think that the best way to do this would be to use the acf/save_post filter https://www.advancedcustomfields.com/resources/acf-save_post/ with a priority < 10. This will run before ACF saves the values. You can also run it with a priority > 10 because either way you need to look at $_POST to see what fields are being updated.
The main difference is that you’ll need to look for field keys not field names in the $_POST[‘acf’] array.
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