I checked 3 products: 1131284561963, 1131284332587, 1131284332587
It has been changed with only 4 field "variant_id", "inventory_item_id" and "admin_graphql_api_id", "updated_at" otherwise keeped value
I don't recevice any webhook though I registed webhook "products"
How can I know that field change, how can I test that?
Wha actions have been perfomed that changed these field values? Did you perform individual product updates or bulk updates? Via UI or API? Etc etc.
A little context goes a long way. As is, nobody can reproduce your issue and thus nobody can help.
I just took a look at one of the above product IDs, and I can see that an app has updated it ~170 times in the past 7 days. Nearly every time it performs an update though it is sending the same parameters (aside from 3 of the 170 updates) and not actually updating anything, and an update webhook will only trigger if something is changed. The only field that has been updated on product ID 1131284561963 for example was the inventory level, but only 3 times out of 170 PUT requests.
So you should have received some webhooks for at least one of these products, but not many overall given the actual amount of updates that have been submitted.