Editing synced Variable product and adding new attribute with variation does create a phantom variation at Facebook.

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🔎 Isolate the bug

✍️ Describe the bug

Variable product had three variants from a single colour attribute. Added new size attribute and a new variation or size and colour. After the sync was made WooCommerce product got four variations, Facebook product got five. One extra variation was added with the wrong link and SKU but the same variation id.

Phantom variation had link to the 'main' product https://facebook.dima.works/product/new-variable-product/

🚶‍♀️ Steps to reproduce

1. Create Variable product with a single attribute of Colour: Blue, Red, Green.
2. Sync to Facebook.
3. Add another attribute of Size: Small, Large.
4. Mark existing variants as Blue-Small, Red-Small, Blue-Small.
5. Create another variant with Blue-Large.
6. Sync to Facebook
7. See a phantom variant created with the same ID as the newly added variant but different link and SKU.

✔️ Expected behavior

Synced Facebook product has four variants and all the proper attributes.