Will notifications still be sent if the product's inventory tracking is disabled?

If I uncheck the "Track quantity" of a product's inventory in my Shopify admin, what will happen to the subscriptions? Will customers still receive notifications?

No. The app is dependent on the inventory of the product to detect its remaining quantities to be able to determine its availability. If customers have already subscribed to an out-of-stock product and its inventory tracking is disabled afterwards, the app will not be able to detect its availability/unavailability anymore. If this is the case, the product will appear as in-stock when a customer browses its product page since this is the default setting.