There isn’t a way to alter the way that ACF saves the value in the DB.
Using a child theme you could possibly use filters to alter the value loaded by ACF, but I would need more information on exactly how you are attempting to use these fields or how the theme is using these fields.
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ACF PRO’s Flexible Content field allows you to create smaller pieces of UI and compose them into whole flexible patterns. In our latest article, we show how to use it to create swappable site sections and integrate it all in a theme.https://t.co/ZRocH8oJSp