In this case Variant will have the highest priorty over product and collection. That means Tier price offered at variant level will be displayed on Product Page.
Example: Offer 1: Buy 2 for 5% off – White Floral Top
Offer 2: Buy […]

The Collection / Offer which is displayed on Top in “List of Offers” will be applied. Then the next Offer / Collection that is in the list will be applied.
Example: Silk Summer Top is in collection is in “New Collection” […]

If an Offer Rule is disabled then the next Offer which is in the “List of Offers” will be applied.

If a Tiered Pricing for Variant level is applied, that is displayed on priority. Just delete it. Then the Collection level tier pricing will be displayed.