it would be important to know, to which endpoint exactly you are sending the request.
But if I understand you correctly, we might have had a similar issue.
The Product overview in the backend shows the values of the defined default store view (under Stores -> All Stores) which can be confusing, because the product edit page initially shows the values of the default scope (which is not equal to the default store view).
Magento has a fallback mechanism for these values from default scope -> website scope -> store group scope -> store view scope
If you send something to
/rest/V1/products it will be saved in the default store view (tbh., not 100% sure on this one). This is also shown in the overview, but it's not the default (global) scope, which is shown initially in the product edit page.
If you want to save something in the default (global) scope for a product, send it to
/rest/all/V1/products. This will save the value(s) in the default (global) scope.
If you want to edit / save a value for a specific store view (mostly used for translations), you send it to
So in conclusion, sending something to the rest api without the "all" keyword or a store code is mostly just confusing