Custom field value problem (ACF)

Each product has a custom field named product_cat, set up via ACF (Advanced Custom Fields).

This used to export the value correctly, but now exports the following value for each row: (the field value, instead of the entered value, something like PRODUCT064)

field_5a735189478d1

There was a similar issue a few years ago, which was fixed here: https://ww.wp.xz.cn/support/topic/problem-with-custom-field-acf-advanded-custom-fields/

Hope you can help!