ACF (Advanced Custom Fields) is a very capable plugin for WordPress.

I would rank it at the top of my go to list of plugins for doing geeky things with WordPress. I do however sometimes struggle with it’s repeater field. The repeater field is used for adding tabular data (or lists) to posts. The number of items in a repeater field can be unlimited and it basically works on arrays.

The correct way for programmatically adding data into a repeater field is to use the update_field function. I find however the docs on doing this a little vague.

This is the array the repeater field expects to see

Here is the right way to do it

https://support.advancedcustomfields.com/forums/topic/repeater-update_field/