I have an order collection get out via API
How can I change some value in API response via custom module
I have an order collection get out via API
How can I change some value in API response via custom module
As far as I understand, this product_option.extension_attributes.custom_options.option_value it's a value that added via extension attributes.
In Magento 2 extension attributes are not magically saved to the database or populated, so based on this value above have to be added via plugin, observer or even rewrite.
The idea is to locate this logic which is responsible for filling that extension attribute and change as you want.
For example, if this is a plugin you can disable it via di, and create your own plugin which modifies the data.