Hello Soren,
It is not possible to pause and re-enable the products. Instead you can exclude the product criterion and re-add it with positive criterion when the product is available. Since
negative field of the AdGroupCriterion is immutable to toggle this field every time you have to remove the criterion and add it with updated negative field value. Note that whenever you add a criterion the criterion id will change even when you add the same product. Please let me know if you have any further questions.
Regards,
Sai Teja, Google Ads API Team

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