Why am I seeing a "value cannot exceed 100,000 characters" error when saving?

Some types of metafields in Shopify are inherently limited to 100,000 characters in their value.

This can be a limitation when working with large JSON structures, aggregate scopes (product types, vendors, and locations), and/or repeatable fields.

Aggregate scope field values are stored as shop scope metafields in Shopify and each field's value is for all of your product types, vendors, or locations. Thus, if the combined value of a custom field exceeds the limit, we cannot save it to Shopify.

When a field is defined as repeatable, ACF stores all the occurrences as an array in a single metafield, and if the combined value of these occurrences exceeds the limit, we cannot save it to Shopify.

To circumvent this limitation you can make use of the Large sets feature, which extends the character limit to 1,000,000.